NICE! That's great. I researched the two brands against each other, and they seem nearly identical. I went with AirLift only because the people on yotatech could vouch for them, and I got a good deal with the compressor/bag package.
You'll be stoked you did it, I think. I still haven't even been able to test mine out, unfortunately.
The bags were the easiest part of the install (but still not as easy as everbody says, in my opinion). The compressor was tough...lots of lines to run and wiring to hook-up. I'm amazed at how my bags have absolutely no leaks, and are truly maintenance free.
BTW, I don't know what the stock ride is like in Sequoia's, but in my 4runner, when you load it down (or even have people in the back), the rear end gets very bouncy. This is because the axle hits the "jounces" (the rubber cones inside the springs) when the suspension compresses. With the airbags, I don't get that anymore. The car rides a ton better.
And as far as load capacities, it seems like the bags are conservatively rated, from what the yotatech.com kids say. Mine have a maximum capacity of 1000 lbs also. So I wouldn't even worry about overloading...the worst that happens is you have to buy a replacement bag for about $40.
Congrats. Good luck with the install. Sorry for the blah, blah, blah...I'm easily excitable.