It's an interesting question for sure. To wit: My brother rides a Mach 429, and I ride an Anthem. Both 4" frames, his is a little slacker than mine, but that's partly because of the 120 fork he runs (I'm 100mm on the fork). While I would say the Pivot is a slightly more durable frame than my Anthem, he's still had to warranty the rear triangle a couple times because the pivots wallow out on it. When taking into account price vs performance, the Anthem is the clear winner, because there's actually not a lot of difference in the feel of the way the two bikes ride.
When you change up and start to talk about the Trance vs the Pivot, I'd say the Trance frame will be a little more sturdy, and the ride a little more plush. I think handling will actually be very similar to the Pivot. You haven't listed prices, but I'm going to assume since you're looking at a Pivot, that money may be a factor, but ultimately won't determine which bike you buy. That said, I always have a strong look at the warranty. Pivot has been good to my brother with warranty stuff, likewise, Giant has been flawless in their warranty support for me.
Final analysis? You can't lose. Get both of them out and ride them, which ever feels best, get it and don't look back.