It has been very encouraging the number of people who have said to me 'You know? I really didn't actually GET writing tests until I used NCrunch'. I'd be lying if I said this was the original intention of the product, but to this day I see it as one of the best things about it.
There's nothing quite like seeing a whole array of black markers staring back at you from your code, reminding you of the big dark holes in your testing.
The perception of developers of where their time is spent is something I find very interesting. I always thought that an interesting feature would be to try and track the amount of time NCrunch had directly saved them (i.e. by waiting for builds and tests to run), although this would be a bit of a gimmick compared to the core feature set :)
I hold the hope that one day the productivity gains of NCrunch will be so unmistakeably obvious that any developer would be crazy not to get on board with it - regardless of their testing experience!
Cheers,
Remco