unless you are really pressed for memory RAM space, its better to use the register banks for associated interrupt levels.

advantages: speed in responding to the interrupt due to minimized PUSH and POP instructions. if you have a critical interrupt exclusively assigned to a level, you can leave some partial results in the registers. you can use less stack space because your interrups dont require all the pushing and popping (sorry about you guys writing in C; all bets are off on their reliance of stack size).

disadvantages: you lose use of the register space for other purposes unless you have an activity that is mutually exclusive from the associated interrupt being enabled; ie, the register space could be used for a communications buffer during a diagnostic printout when certain interrupt supported equipment wouldn't be connected.

the real question might be, "how do i condense my use of register/memory space for more efficiecy?" i've found that most people in our business are really really really sloppy about memory consumption; i've written about this enough in the past (deleted or not).

duh