Only had stuff done properly by Stardelta.
I forget the guy's name, but they did sound quite a bit thicker than my own masters of the same tracks, so that was good. I can't seem to find the email with his name in it, but if you want I can tell you the name of the EP and you can see how it sounds (whether or not you like my composition and mixing, lol) for yourself.
Best thing, or at least what I've always wanted to be able to do (as far as having other people in/on my stuff w/o a 'feat.' or something) is find a place you can actually go and sit with the person treating your music. I think the main cause for producers not to like the masters they get back is a difference in vision. Like if you can actually be there and say you want them to do more than "just make it louder please", then any remotely good engineer will be able to get the job done.