I have them on my M6 and love them. Although I do live in sunny Queensland Australia, so I do see some hot weather here.
Most days for me is shirt and tie, so jumping into a hot car with standard leather seats mean I have a sweating back within 5 mins. With the vented seats, I have no such problem. Love them
With regards to things getting into the holes.... well I have my car professionally detailed each week, and I'm a car nut who never eats or drinks
in my car, so that's not really a problem I have.
My suggestion is that if you live in a warm to hot climate... go for it, you won't regret it
Scar