With the memory card you'll get roughly double the performance out of the A1200, which might be enough for your needs.
But, with 8mb on the card you wont be able to add any more if you need it, or use the PCMCIA slot for a network or SCSI adapter, or add a faster CPU.
Like Doctorq said, low end accelerator cards go pretty cheap and give you more room for future upgrades. Just depends what you want to do with your amiga, and how much you're willing to spend.
