I've had the kevlar air mesh pants and jacket for a year now and they've been a very good investment. The pants have softened up after about 6 months so they are more comfortable to wear. I also have an Aerostitch Roadcrafter that is about 13 years old. It's still in great shape, although it doesn't get much use now that the Motoport gear is in house. Riding in 100 degree heat works fine with the mesh, although you have to be careful to heep hydrated because the air flow will suck the moisture right out of you, but you won't get overheated from baking in low airflow gear.
Under 70 degrees, you will need the liners or a light under layer of some kind. By 60 degrees, you will definitely need the liners or a solid fleece layer. The fabric flows that much air, especailly the jacket. You probably don't need a liner under the pants (assuming you are wearing jeans under them) until around 50-55 degree weather depending on how long the ride is.
I can't compare crash and slide performance, knock on wood, but the Motoport armor definitely has much more body coverage tha the Stitch. For the price, especially here in Texas, the Motoport gear rocks. In Seattle or Miinneapolis, I might prefer the Stitch.
Quality wise, you can't go wrong with either set of gear.
With the Motoport, the one thing I'd do different is buy the shorter jacket, versus the parka length. The extra length seemed like a good idea, but on the bike, it's mostly in the way, and tends to bunch up the jacket.