I'm asking myself the same question. The main advantage is that the speed can be ramped up or down in V2 which wasn't possible in V1. But then velocity ramping has been available in Vegas Pro for quite some time via a velocity envelope.

Also, I haven't used V1 for a long time. I guess that I'll give V2 a go via the trial version to see if it offers any clear advantages - though one advantage would be that V2 also has inbuilt Mercalli 6 stabilisation which means, I think, that velocity changes and stabilisation - if needed - can be done at the same time rather than as two separate processes with two separate renders. That alone could make V2 worthwhile. Food for thought.