I've got an xbolt stainless stalker in 300wsm (not the mountain pro) and a 300 wm PH2. They are quite different. To sum it up, Browning is nicer to carry (lighter, shorter, trimmer, has a flush fitting mag so it is great for carrying in hand) and the seekins is nicer to shoot (heavier, good vertical grip, better feeling trigger). The xbolt goes hunting more.
I'll say the browning sporter stock ergos are one of my favorites as far as more traditional sporter style stocks go from a shooting standpoint. They are a very nicely balanced set up. Dont have drop in comb/drop at heel, have a great recoil pad, and the grip is actually close enough to the trigger to be useful in making good trigger pulls. I'm not sure what the max magazine COAL is in the browning but i'd almost guarantee the seekins allows for longer COAL.
I paid $800 for my stainless stalker xbolt in 2014. It shoots better than the 2 factory seekins 300wm i had They warranty replaced the first because it was unacceptable. The 2nd was also unimpressive with the bullets i wanted to shoot so I rebarreled it on my dime rather than spend more time/money on ammo for a 3rd. Despite my poor luck with them, i believe they had some bugs early on with lots of rifles that have since been worked out and think the havak platform is very hard to beat for the price point.
Seekins has a better setup for rebarreling if you actually shoot enough to go through a barrel.