BTCC has some very odd rules to keep things competitive, the RWD cars are hugely disadvantaged with regards to that so I never expect them to be the popular choice. Besides, they're building cars to win, not to be enjoyable.
As I said, suspension and chassis work has come a long way, but it still can't beat physics. I have no doubt it'll be quick, but how much time you spend fighting the car as opposed to driving the car remains to be seen. I'm as keen as anyone to drive one, but very little could persuade me to buy one.