Just to add some positive input. I am presently a member of an SR20 rental scheme and find it to be a huge improvement on my old club rental. This is due to the lovely aircraft & the fact that it's readily available. As a customer, I am prepared to pay slightly more for these 2 factors.
Unfortunatley, what the compay wants and what the customer wants will cause conflict in the business model with regards to availability.
I don't really see the potential to make money with this set up, or anything in GA for that matter!