I think, as long as the memory's adequate for a single page, the system can always spool it a page at a time.  However, this obviously needs the machine to hand-hold the process, so it slows things down.

 

I've never had problems with the 8M in my laser.  I think more memory could lead to faster returns of control (esp. in a system like Win9x where the printer locks everything while spool), especially if it can eat the job from several users at once.