As most of you probably know, the PVC board and the sintra are not the same materials.
The PVC works great, but it does have a few disadvantages when compared to the sintra (which is a "sign board" material used by sign makers).
The PVC is a bit more brittle and is a bit more prone to chipping. I prefer the sintra, but is because I build for musky applications and don't want to risk chipping during the building process. The risk of chipping is small though overall.
Both have less buoyancy and bounce than a number of types of wood. It has a slighter duller action in the water. That is small trade off and the differences in action are negligible overall in my opinion.
As far as building a long-lasting bulletproof bait, both PVC and sintra are excellent. Both are slightly more difficult to work with in general. Both are a little tougher to sand, but for musky bait building applications that is a lesser consideration if you simply apply a coat of epoxy prior to painting.
I have quite a bit of the sintra in the basement now, but I have so many projects going on that I've sort of set it aside and having been using it as much as I'd like to. I did build a twitch bait from the sintra recently and it is nice to skip the sealing process and its nice to know that water will never penetrate the bait during even the harshest conditions.