I'm of two minds on this. The main reason I disagree is because a sneak roll covers enough ground quickly enough to be a sprint with the bonus of moving unseen and backstab damage. If rolling cost less stamina it would break the trade off benefits of moving slowly for stealth bonuses. More Iframes from skillup? I guess, but it would have to be so fractional to keep it from being broken as to make it hardly noticable compared to the baseline. Less stamina from skillup? No, because then everyone would stealth roll cross country.

Probably best that we don't have a dodge/roll skill. They could tie it to encumbrance the way ds does and this is kinda soulscraft already, but do you Really want to cross that line?