alside "clip in sill" design

Ok so not to pick a fight in any way, but what in the heck is a clip in sill design?? every claimed "contractor" on this site says thats all alside uses in all their windows, but my question is about their Preservation line. The only somewhat-descriptive explanation I could find anywhere (and i looked everywhere I could find to look for a couple days) was that it wasn't fusion welded because alside won't invest in the machinery to do so. However... Preservation windows are fusion welded at all 4 points at once - I have attatched a picture from inside their factory in Akron. Now the only other complaint about Preservation is the bulky frame. As i understand it, thats a deliberate feature to ensure the longevity of the life-span of their windows. My buddy got them installed not too long ago and I think they look quite wonderful. Can't say i miss the extra 10 square inches terribly, especially with a .17 U-factor, and .21 SHGC rating (this number was from a DH window that was 36x60 (96 U.I)) - which to me, means a good bit. Just curious!
Thanks in advance!!

We are referring to a sill where water not only drains down the sill but also through the frame and out weep holes. This is a very old/ poor design. Why? Aside from losing glass, those weep holes invariably clog and you are left with mold and whatever debris the water brought through the frame. It is can be extremely difficult to unclog those weep holes.
You want a " true welded" one piece sloped sill where water ONLY drains down the sill and NEVER through the frame.

The welder above means nothing as far as the clip in sill we talk about. Both the clip in sills and the sloped sill windows use these type welders.
Masterext addressed the rest.

BTW, not all Alside windows use the pocket sill. The Excalibur for example uses a true sloped sill. Our problem with that window is based mostly on air infltration issues that we have all seen when using them earlier in our careers. The Preservation is definitely the cream of the Alside line.
Being bulky was a good feature in the 1990s. The fact is, the bulkier the better. With today's window technology bulky windows are dinosaurs. The strongest most airtight vinyl windows on the market now have much thinner frames. Just look at HiMark, Okna, Sunrise and Softlite for example.

I will add that although the excalibur is a sloped sill, it is very flimsy. If you take an okna or soft lite sill and place them side by side with the excalibur, you will easily the difference in structural integrity. you can literally squeeze the alside excalibur sill with your fingers which makes me think that after a few years of opening and closing the bottom sash, the sill can eventually bow and cause water to puddle.

I should have added above that there is not a window in their line I would personally install into someone's home. I just don't like any of them.
When I said the Preservation was the cream of the crop in the Alside line, it was not anywhere near an endorsement.

Pick and enjoy what ever window you want.
This is the USA.
Wish you the best results.

I think that the 8000 series is their best product.
The Preservation is essentially a Ultramaxx/Sheffield with more bells and whistles. Pretty bulky (less glass) and typically fetches a "premium " price because it is a private label line. The thermal number of .17 (triple pane krypton) while being a great rating, is less impressive when compared to other products that achieve .15 or .16 with better air infiltration ratings to boot. Regarding the "bulky frame" adding strength, look at it like the bumper on your car. Back in the 70's when crash test standards changed, we had these giant ugly steel bumpers protruding from the front and rear of every car. Now, they are much smaller, integrated into the design, and actually provide more protection. Such is a bulky window design. Newer models have superior engineering that provide equal or better strength/longevity while gaining glass area looking nicer. A great thing to look at would be the structural ratings of the window. The design pressure and air infiltration ratings will be very telling as to the manufacturing tolerances and strength of a given assembly.
On the Excalibur/Revere Berkshire/Enviroview, it has a welded in sloped sill, however it still has open channels that water is directed through and out weep holes. Basically, it doesn't have the "bulk" and glass loss associated with most pocket sill designs (or snap in sloped sills), but it does still channel water through the frame which is undesirable, as along with that water goes dirt, debris, bugs, etc that can slow or stop the water flow and cause all kinds of issues from minor to severe.
The are certainly far worse products than those mentioned above, but when considering a product, I like to look at the thermal and structural ratings, potential design flaws, and overall reputation of the manufacturer to determine where it falls in the spectrum of quality and performance. I can't speak for others, but that is why I sell, install, and recommend the products that I do and shy away from other choices.

Thanks for the added input Windows on Washington. I agree with your points and they are certainly in line with what I was getting at, which is that in much the same way that cars today are both safer and look better than a big ole' scabbed on steel bumper in the mid seventies, the newer window designs achieve superior structural ratings without sacrificing looks or glass area. I was really addressing the OP's questions as to whether or not "bigger=better" as it pertains to a vinyl window frame, and my main point is that "bigger" is bested by superior engineering and technology.
You and I are of like mind on the U-factor as well. As I had already stated, .17 is a great rating. I was only pointing out the fact that it is not a particularly impressive achievement as the OP had wondered, as there are apples to apples products that achieve superior ratings. As a matter of fact, I think that triple pane argon units with u values in the .19-.20 range really hit a sweet spot of phenomenal performance combined with a reasonable price given that krypton gas (used in the .16-.17 examples) is outrageously expensive in most cases.

I've had mixed results with alside. Some issues here and there, but they always stand behind their products. You definitely lose some glass with the Sheffield and Ultramax though. I prefer the snap in sill because at least it is funneling most of the water out via before it reaches the frame.
That analogy sounded pretty clear to me fwiw. Bulky old designs have been replaced by newer streamlined versions that are better and stronger.