I'm looking at adding mini blinds to some of my new windows, do I have to worry about the blinds scratching, ruining the Low-e coating on the windows?
No. The low-e in most internal blinds windows is a not a soft-coat and therefore can hold up to the abrasion of the mini blind. You will not find a unit with the blinds inside the IGU with argon fill.
The blinds have a lift and tilt function, do these generally hold up for the long term or are they not worth the hassle, and loss of gas filled windows?
If they are well designed, yes. They are much better today than in the last 5 years. While they only represent a small fraction of the windows we have sold/installed, we have yet to have any problems in the short time they have been out.
I'm torn between blinds vs no blinds since we have some windows that face south and get brutal afternoon sun, they will help with sun control in my kitchen. However I see most warranties only cover the glass with blinds for 10 years or so. It makes we wonder if this is indicative that mini blinds/glass does not hold up well with mini blinds installed.
Standard low-e will reduce they amount of the sun's radiant heat by more than 200%. Keep that in mind. If you are really worried about just the heat, you can opt for more aggressive Low-e coatings and get that reduction to more than 300%.
Should I look at other glass options like the solarban 70 to help control the sunlight in the kitchen.
Depends on where the home is located and what the efficiency goals are. Many folks that are in cooling degree dominated climates will be better served by lower SHGC windows. If you live in an area with a heavy heating season, going with the lower SHGC window can be a net negative impact as compared to the higher SHGC window.
Again, standard, 2 soft coat Low-e (i.e. Cardinal 272, Guardian 7138, Solarban 60, etc) will reduce radiant heat by more than 2X right off the bat.