I think a lot of the issues are stemming from OS 9.1 but you'll hear varying reports on it..the 733's are a rockin' machine indeed and you just have to make sure you have all of the latest firmware updates and so forth..also issues stemming from OMS which as all know is in Limbo(thank you Gibson!!!) and not being supported anymore..
I think the question on everyone's mind is what is going to happen with it and is FreeMidi(who is Midi and why are we trying to free him?!!) going to take its place!! I think what really matters is what SCSI cards you go with and video cards as well..as we all know there are countless configurations in a system regarding third party plugins and hardware drivers not getting along with each other. You just have to be careful as to what you install and howyou install it!!
Opus

Wait until macworld in 2 months. I believe if not then sometime from now till fall the mhz gap will be narrowed. This would mean for the price of a 733 you could have much more computer, also it means that the 733 will be a lower end model.