I do like the helmet and/or suit damage when it happens in the show. That seems to work better than the just going helmet-less scenes with the actors. Kamen Rider can pull it off a little better, but you begin to notice the difference in Sentai and even Power Rangers. The actors don't fill out the suit as well as stunt actors. Which, in this, case, sometimes works better if they don't do it. For example, Genta's/ShinkenGold's suit-actor was a little more stout while Genta himself is as skinny as a rail. Watch Shinkenger again, you'll see what I mean. Another example is when the female actors put on the suits, and the suits look too big for them. And I don't think I have to mention how different it is when Saban/Disney has to make their own Power Ranger suits cause they can't get the ones from Japan.
In other words, there seems to be an art to doing it just right. For example, in the case of things like Kamen Rider Blade or GekiRanger, those shows did it just right. The characters received helmet damage at the final, bitter end of their battle scenes; thus you were too swept up in the action to really notice if there's been a change in height, how well the suit fits, or whatever. I guess, if the show is lucky enough, the stunt actor might look enough like the real actor that they'll keep using them even for the helmet damage scene or whatever. Kamen Rider Hibiki is one of the few lucky exceptions. Hibiki's actor, Hosokawa Shigeki, was actually pretty well built himself. He was able to fill out the suit just as much as his stunt actor, thus it became more believable when you saw Hibiki helmet-less.
Know what's funny? I had heard that Kuuga, or some Rider show (not sure which), had used a lot of its budget on battle damaged versions of the suit. But as time went on, the production crews realized it was too expensive to keep doing that, so they cut back. But if it is true, it makes you look at the things they did for Kamen Rider OOO and realize they could have used that money to give us a much better show instead of a billion suit combos.