Interesting. I suppose one will judge this strategy based on the value (if any) they put on SMs (or to a lesser extent on PMUs). I already buy into K or higher almost every time I fly. So, how many SMs is it worth to me to guarantee an upg on a route like ORD-SLC? I dunno. Maybe 100? Even with the 50/50 chance of no collection, I'd be inclined to roll the dice on the shorthaul (especially as a PM on a relatively high fare) and save my miles for BE TATLs/TPACs.