The Vanguard (and Howa) certainly have plenty of after market options.
Firing pin/spring upgrades
Drop Box Magazine systems
They don't need "truing" (IMO).
The S2 is much better than the S1, a buddy now has 3 S2s to my 3 S1s. His shoot nearly as well as my, now custom, as in all that is left is the action, bolt and trigger guard and semi custom, as in still has the original barrel which will be changed when it stops shooting sub 1/2MOA.
Right now I'm much more into Mark Vs and I'm using some R700 actions for my 26 Nosler based wildcats. I'd much rather use Vanguard S2s but I'm using take off barrels to cut costs and as testing/fire forming platforms.
Mmm MkV *drool*
The S2 is, by most accounts, far better built than the S1 so that makes sense. Great rifles. The options from Howa and Weatherby are just crazy
I mean these are just some generics of their respective websites. Chamberings from .204 ruger to .375. Lots and lots of variety