Personally, I would never recommend anyone who's not extremely versed in the Windows Registry and it's structure, to use any Registry Cleaners.
They're not needed in the first place since 500 keys may take up a whole 50Kb's of space, so there's no space savings to be had, and any orphaned keys will NOT slow down your system...they're "orphaned" which means nothing is trying to access them anymore, and since it only takes a few milliseconds to load the entire registry, any time saved loading is not measurable. Most reg cleaners will also list false positives at some time or another, so unless you're qualified enoug to recognize those as such it's best not to use one. And most folks never go thru the list anyway so...bye-bue to a needed key now and then.
About the only things that do any real good are Registry Defrag and Optimizer that rewrites the reg hives into disk areas that have faster head access times. Still, it may sabe 1 or 2 seconds overall, so do you want to take the chance that during the process something doesn't become corrupt?
Registry Cleaners are a good example of a program that made it's own Customer base by telling people how awful it is to be without one, without actually offering any real proof of such.