Mach Punch and Ice Punch combos are obviously not as common as Sneak+Hammer Arm, and I think the ability to hit stuff like gengar with Shadow Sneak and the ability to actually dent steel types apart from mach punch is more valuable. However, the Mach+Ice Punch combo allows you to hit flying types a bit more efficiently. Now, flying types that would actually be hurt by Ice Punch would be Staraptor and Togekiss, both of which outspeed rev and would either ko or massively dent it anyways. Due to the fact that even with Ice Punch, Togekiss and Staraptor would still pack a shitload to rev, that's one of the reasons why I would not use that combo. I'd rather switch to a counter than hope to survive and kill with IP. Perhaps it would do well with predicted switch ins, but that's going a bit too far, I'd say. It's main selling point is definitely the ability to hit zapdos super hard, which is a pretty valuable trait.
Regarding Hammer Arm:
I'm not sure if it's just me, and I'm pretty sure it's not, but I'd trade a shitload of a punch for a mere drop in accuracy as opposed to 2 weaker moves. If I had a move with 100 BP and 95 accuracy with stab, I'd choose it over it's 95/100 acc counterpart with stab. 150>143. Safer option. Hammer Arm is the main attack of Revenankh, and is definitely part of it's main set (Shedrest with Bulk Up). If x attack missed because of a little accuracy hax, it's nonetheless still a viable option as long as the risk of using that move with less accuracy is worth it. For example, you have Hydro Pump used over Surf for many waters due to the fact that it hits a lot harder. Likewise, this is why Sneak+Hammer Arm is more common than Mach Punch+IP. It's just going to hit a lot harder and pose much more of a threat to your opponent's team.
And that's my input for now.