That depends.

What's your budget? Are you looking for the entry, mid level, or hi-end FireGL card?

If price matters, the go with a 128. If not, then splurge for the X2.

Worth the trouble? I would think so. When I upgrade parts, it's usually to a newest item so that I don't have to upgrade very often. Im looking to upgrade my vid card soon as well. Still running the Radeon 64MB DDR - which was top of the line when I bought it. Now, Im looking at the X2. Just gotta save those dollars first.