I think it's a standard sized threaded port in the lid, so I think you can change styles. I know I've replaced different types of pressure relief valves with the ring type (my preference). As I've said before, life is too short to waste good beer by having shoddy kegs. Keep a selection of miscellaneous parts and replace them the minute they seem dodgy. Sure, try to clean them first, but if they won't consistently hold pressure, get rid of them.
Unscrew the bad ones, check the threads for gunk (toss it in some PBW to be safe), screw in the new one, and test it out. Might as well inspect/replace the O-ring while you're at it.
Use whatever type valve you want, as long as it works. A keg isn't a keg unless it holds pressure. Otherwise it's just a fancy bucket.