The high-end Ibanez guitars have floyds. Low end have knock-offs but of similar construction, so as poontang says you can go up and down on them. I've got mine set up so I can dive but can only go up a little (so I don't break strings!).

All the floyd trems have the strings blocked in at the bridge, so no ball-ends. People do string them backwards and use the ballends at the machinehead end to save the hassle of cutting them off. I just cut them... always have and not a problem. I can string a floyd in 5 minutes from nothing...

I don't have any problems with tone or sustain. Check out some Ibanez endorsees... do thet have sustain problems? Ibanez don't get flak that I hear - their top end guitars are as good in my opinion as anything else in the ballpark (if not better). The cheapo ones are still good for the money, but pickups might need upgrading.

Maybe look at the JS2000? It's a radius body (like an S but fuller) and has a fixed bridge if that's what you want...

The hardtail RGs are often neck-thru as well, so you should get better sustain. How long do you want a note to ring for? With a bit of vibrato I can carry a note on a JEM/RG/JS/Floyd whatever until I'm bored of hearing it...