From all the negative stuff on floyds you post, I can't help but wonder if you just need to experiment more, or get it setup slightly differently. I don't have the problems you suggest, and I would imagaine the other floyd users on the site would say the same... I wouldn't use them if the tone was crappy.... Steve Vai and Joe Satriani wouldn't either....

I can use my trem quite heavily and not have problems running out of tune. I don't have sustain or tone concerns. Forgiving my possible ignorance of your setup, if you're running a serious signal chain with effects and (mostly) distortion, how much of the resultant tone to you think is down to the guitar anyway?

You should talk to James Tyler or Tom Anderson - they'll make you a guitar exactly like you want, and be able to advise on the tonal properties of certain build combinations...