Other thing is the surprise effect. With Traitor's Clutch in the graveyard, your opponent will almost always be able to count how big Tog can get. With Shadow Rift, you get a free dredge and surprise effect. I think 1 Clutch and 2 Rift would be a good balance. You free 2 Uncommon for more buried alive.
I don't think surprise counts for much past the first game (or past the first Rift, assuming you used it to dig for a Tog in the first place). I'd consider it a very very small factor (and easily balanced out by the fact that Clutch is immune to hand destruction). TBH, I wouldn't be suprised if a veteran opponent was able to blind call that you run
something to make the Tog evasive. There's a reason people ran Berserks with him back in the day.
I do think either (or a split, as suggested) is probably preferable to Wonder.