I also got a great deal on a Sako 75 in 300 Win Mag 7 years ago; couldn't pass it up. It's not by any means my ideal rifle since I like short action, light rifles (M70 Featherweight, Mountain rifle, etc...). The extra kick took some getting used to at the range but now I can shoot it all day w/o a problem. The extra weight/length can be distracting in the field too.
I have no experience w/ the WSM though I do like shorter actions. The first time I took the 300 Win Mag hunting I failed to cycle the bolt all the way for a follow-up shot......I can still hear the <click> [&o] Anyway, I got used to it (and I got the deer).
Cheers