I noticed that during number entry, pressing (even repeatedly) the EXIT key does nothing. I don't know if that's the intended behavior for some reason, but wouldn't it be nice if pressing EXIT during number entry just canceled that entry, without modifying the stack at all? While using my 34s, a couple of times I started entering a number, then realized I didn't have to, so I had to clear x and roll down the stack, and I lost the top level of the stack...
Cristian