I have used my 300wm for driven boar, although it was bought for longer distance, and plains game. I load Norma Oryx 200gr for boar, and it is very effective.
BUT, and this is why I'm not so keen for driven, to get the benefit from the 300wm, or in fact most magnums, you want a circa 24-26" barrel, and that's a lot to swing quickly, at very short ranges, common on driven hunts.
I'm fortunate to shoot quite a bit of driven, so I can justify having a 9.3x62 barrel for my Blaser R8, and other barrels for other hunting.
I would want to choose the best calibre for the vast majority of your hunting, and compromise if boar will only be occasional. Now if you can justify a change barrel rifle, get a barrel for stalking, and if you do book to go driven, buy something for that ?