I really wish Sun would make patches and updates available at a finer-grained level. I wouldn't mind an alpha or non-stable build of the JDK, and would accept a disclaimer to the effect that I know this a development build and won't complain to Sun about problems with it.
But this doesn't seem to be the way Sun likes to work. For example, the bug regarding double-precision floating point performance: math with doubles is 1.5x - 4x slower in 1.4 than it was in 1.3. And Swing/Java2D uses doubles heavily.
I want the choice. Are you listening, Sun?
Cheers,
Colin