I haven't been to Union at much over 1000, or seen Hollywood when it's really "in" which I think requires over 1000, but at 300 - 500 the bottom hole is pretty fun, if you like trashy holes. Much higher than this and it washes out if memory serves me. Maybe it comes back in at much higher levels.
The top hole is fun at every level I've paddled there, but is almost boring at times. Hard to get vertical b/c its shallow, but you can flat spin and get a just a little vertical all day long. Maybe with the newer boats you can get a little more vert and open up the possiblities.
While I've never seen Hollywood at its best, I have seen some guys doing loops, blunts and some other tricks on it when most of us paddled right by. There is a sweet spot on the wave that is easy to miss. But, once you find it, you can do some good stuff.
Anyhow, my 2 cents. I pretty much learned to play boat at union and confluence duriing rain storms, so maybe I'm partial.