AS
Not sure there is a right or wrong answer to the first part of your question.
I like the driving range and playing off the mat as I don't have to pick the balls up! Gets the swing into something resembling a rhythm and you don't get wet if it rains or snows! On the minus side, there is a charge per basket.
My club has practice grounds so if the weather is good and I'm feeling energetic, I can use the grass or mat facilities but have the *** of picking up the balls. It is, however, free to members.
As far as range balls are concerned, they are battered on a daily basis, collected and washed mechanically and are built to be robust - We can't expect them to react like a new ProV1. You can get them to spin for your Vokeys but there is a drop off in longer club distances. Accurate distances can be checked with a Trackman session if needs be.
JT

i personally hate playing off mats, club bounces off mat and into ball so don't get a true reflection on how you are hitting it. id always choose off grass and re teeing up myself each time. i appreciate 'JT's' view on the rhythm but i feel sharpening pre shot routine is just as important as anything. my local range has the self loading balls which is clever but i always avoid them for the very reason said above. it is horses for courses though. any practice will help

Sam,
Take your point...
You'd be making a bit of a leap of faith describing my "pre-shot routine" as such.
I'm not convinced that I can remember what it was last time I played... Then again, I have to admit that I struggle to maintain a consistent pre-shot routine for more than a hole or two at the best of times.
JT

I agree that any form of practice is good, but playing off the mat is not the same surly