I built up a Blue Pig a few weeks ago, riding it mostly in the Peak – really like it, it's kind of interesting because of its geometry, low front end, steep seat tube etc. I've ridden a 456 briefly as well. My take on the Pig with a Pike is that it's quite a heavy thing, goes up and downhill like an unstoppable steamroller, with just enough flex out back to sort of go over and around things effectively, but sort of loiters along flatter terrain like a sulky, whining teenager with his hands in his pockets.
If your local riding goes mostly up and down in a techy sort of way, I'd go for a Pig, but don't expect it to be light and sprinty. If you have more flattish singletracky stuff, then the 456 is going to be more of an all-rounder, I think. Then again, if you're going to stick a 160mm fork on whatever it is, you're probably not going to be building a light, agile, singletrack-friendly rapier of a bike whatever frame you use, are you?
Anyhow, that's my very average rider's take on it 😕