Well I think r&p will be as good if not more accurate than belts. Loads of people are having great success with r&p, also with belts for than matter too. You haven't said what you will be cutting, if wood a few thou is more than accurate. If you want mega precession you will just have to man up and buy top quality ground ball screws.
Personally I think people get caught-up looking for 0.00000000001 accuracy when its not really needed.
Search these forums as its all been discussed before and ultimately comes down to budget.
Good luck with whatever path you follow.