I have a Whelen AI, but it was a new tube so cost wasn't an issue, a bit extra for the dies. I had that rifle built about 15 years ago, at the ripe age of 21-22, so I had only been handloading centerfire for around 7-8 years and had no idea how little gain was involved when both versions where loaded similarly..wasn't much readily available info on either at the time...that I knew of anyway.
With a new barrel I'd do it the same again, cost a little more for dies. You are going to shoot the rifle a bit to break in the barrel and see what it does anyway..why not be forming brass. Mine shoots the Remington factory stuff into some pretty small groups if I needed to use that ammo in a pinch, but it would require a serious re-zero due to the weak-titted loading. Five full power loadings, after forming and trimming, and still no need to trim the brass is nice if you want to shoot the rifle regularly.
I get some pretty good velocity out of mine, but as JB said, it does have a 25" barrel and I do load it to it's potential.
Now if you ever anticipated the need/want to sell the rifle, I would certainly go for the standard version. Another issue with mine, your rifle may differ, was that it required some work to make it feed smoothly in AI form...where it fed the original 30-06 rounds quite well.
