I meant that I was comfortable with either other the sales locations and installers. I have talked to several people I know who have had windows installed by the installers out of the location I am going to and they have had nothing but positive to say. I am unsure of the merchandise and what’s the better deal.
I am going to sound a bit like a broken record here but I am also not a fan of either.
The Pella 350 is a newer design from them and is a great advancement in terms of their vinyl offering, however, it still has a pocket sill.
The pocket sill is a huge drawback in my opinion and is what I would consider an Achilles heel when there are so many good slope sill windows out there. That all being said, the Excalibur (Alside - Window World 4000) is a fully welded sloped sill but has just as many other issues that probably add up to the net negative impact of a sloped sill.
You could inquire about the Window World 6000 (Alside Sheffield) for a comparison but it is a huge bulky window as compared to the Pella 350 and Window World 4000.
I realize this probably helps you exactly 0% but that is my honest impression. Is there any way you can look at some additional options?