John, the impression I get from other Yamaha users who are much, much more into styles than I am is that many of them buy or trade style files, then take some time to "tweak" the styles using one or more programs designed for that purpose. They will typically do things like "revoice" the styles to make sure the styles are using the best voices and drum kits that their particular model has available, edit the voice parameters, edit the reverb and chorus and other effects used, etc. Some even get into editing the musical parts-- the bass lines, chord types, intros, etc.
So basically, I wouldn't write off the style files you purchased just yet, because you might be able to tweak them to be more to your liking.
If you haven't already heard of it, you might want to check out the PSR Tutorial website and forum. The main site offers collections of style files on USB thumb drives, and while most of them are likely intended for the Genos, Tyros, PSR-SX, and PSR-S models, many of them might work with the PSR-E models, or might be able to be converted to work with PSR-E models. You should also be able to find articles and programs for style editing.
You can also check out Jorgen Sorensen's site, jososoft.dk, as he has programs that he's written, as well as articles and links that should be very helpful.