Well, if the cost for an OS key was lower for this model, I'd say go for it, but Kronos is right, you probably want something more powerful.

I have been debating the merits of a key for my iBook (faster than the Powerbook you are considering, but with even less vram).

Oh, and since the 1.5 GHz model Powerbook can also feature 128MB of vram (a special order option) I would consider that as well (less than 200 MHz is not significant difference).