I've got both the x-ray and the bravo for my tikka's and between the two chassis, I've got to say that I prefer the x-ray. As mentioned earlier, the thumb-shelf on the x-ray is extremely comfortable and just feels like a natural spot for your thumb to lay. I don't really use a traditional pistol grip hold when shooting so the thumbhole is only beneficial for rifle manipulation or handling, at least for me...
The bravo does have it's "pro's" list when compared to the x-ray. The bravo is lighter and it does have a more familiar feel to that of a traditional stock. The other added benefit is that the bravo is available for the 10/22 platform. I ended up purchasing that for my 10/22 so it's nice to have the same exact nomenclature for a chassis on the two rifles.
In all, you won't be disappointed with either the x-ray or the bravo because they're still very similar. Hope this helps