If the 7mm Weatherby is what you want, get it. There's certainly no disadvantage to it versus the Remington version, other than the cost of ammo. And there is the additional velocity, which while it's not a whole lot, it's about the same difference there is between a 308 Winchester and a 30/06, and most people consider the 30/06 to be a significant increase in performance over the 308.
The fact that you have already hunted with the 7mm Weatherby and obviously have great confidence in it, is the best reason of all to go with that cartridge.
As far as barrel length, I believe the Weatherby uses a 26 inch barrel, while the Remington is most often seen with a 24" barrel.
Recoil should be similar between the two cartridges.