Bob, Scarp 1 is like the little sister of the Scarp 2. I believe the majority of points in Will's review (it has been a while I read it) should apply, except that the Scarp 1 is smaller in all aspects (less surface to be attacked by wind, smaller footprint, etc.).
No particular tunnel in mind, just based on Roger's comment on how he pitches his =) I know that a Stephenson 1 P tunnel has been used on a Nordkalotten (Scandinavian long distance trail) thru-hike with good performance, but then again, Hilleberg is from this region and knows their trade. Hilleberg vs Stephonson is pretty much a question of preference, the Stephenson "marketing" is a tad odd, but their tents have a good reputation. And as you probably know, Hilleberg tents are widely used in this community, also by BPL staff (Ryan Jordan has a Soulo ;).