I really wouldn't call RD softish. I've got the diamond plate and the raised areas are subdued. I don't have trouble rolling anything over my floor. Why don't you request a sample and determine for yourself.
We do have a smooth top modular surface ( call for a free sample). But I am confident that you will find the tread designs on RaceDeck to work really well with creepers and other rolling items in the garage, they were all designed with this in mind.
Thanks