Here's a very quick comparison. Keep in mind that I have no field experience with either the SL1 or the Rainbow, just a handful of setups in the back yard so far. I do have considerable experience with the Hubba – but none of it at elevation: all of my hiking is in the Midwest, and 500' is "high" around here. So what follows may not be applicable to your 10K elevations.
The Hubba is a wonderful tent that almost pitches itself. It's versatile, allowing a fly-only, mesh-only, or "traditional" fly and mesh pitch. This gives me a lunchtime shelter, a non-stuffy shelter in buggy August weather (80 degrees/90 percent humidity), and a pretty much bombproof shelter the rest of the time. The long-side entry makes it an incredibly convenient tent to use; the high point of the tent is right where you climb in. It's stable. However, at 3.5 pounds, it's also heavy; also, the floor space is limited because the tent is very narrow – the length is fine, though. (Narrow cuts both ways: it cuts down living space, but it also lets me pitch it in some really tight spots where the SL1 and Rainbow wouldn't fit.)
The SL1 seems pretty roomy at first blush – the trapezoidal shape gives you good shoulder room, and space to store gear, plus the pitching versatility of the Hubba. However, I find the end entry a bit awkward (but remember, I'm comparing it to the Hubba), and I find I can't get into it without brushing my head and shoulders against the mesh. The high point of the tent is a foot or so beyond the door, so the door is low-clearance. But, it's lighter than the Hubba by half a pound. It's not really freestanding, but can do in a pinch (you lose a lot of living space unless you stake out the foot. It does get a "what were they thinking" design award: the door area uses clips to attach the body to the fly (just like my beloved Hubba.) However, you have to thread the rest of the pole through fabric loops – not nearly as fiddly as a pole sleeve, but aggravating in its own right when you thread it through 3, then discover you missed the first one and have to start over. (This is not something you want to expose the tender ears of small children to.) Overall, this tent reminds me a lot of the Zoid 1 I used to use (except the Zoid had a side entry.) Although the fiddle factor is a little higher than the Hubba, this may turn into a viable replacement tent for my Hubba, letting me save a little weight without radically modifying my overall approach to gear. I have to admit that I got a little bit of the warm fuzzies when I stretched out in it.
The TarpTent Rainbow is a truly innovative design, and I see tremendous potential in it for saving weight (especially since I'll rethink the rest of my gear; the total approach will add another 2 pounds to the pound and a half the tent saves, reducing my total load by about 25% – nothing to sneeze at.) However, I didn't get an instant case of the warm fuzzies with this tent. It has a higher fiddle factor than the other two. There's the poles sleeve to contend with (the Hubba's clip system spoiled me.) You end up doing more staking and tightening/restaking with this one to get a taut pitch. You have to seam-seal it (a one-time fiddle, but annoying – again the seam-taped Hubba and the SL1 have me spoiled.) As noted above, there's a high fiddle factor with the vestibule. The threshold at the door is needlessly high (about twice the height of the other two.) The freestanding pitch is, at best, flimsy (again, the Hubba excels; this isn't a big deal, since I bought the Rainbow fully intending to stake it – I tend to use at most one hiking pole.) The ability to clip and unclip the floor seems overrated – I didn't see any difference in the ventilation either way (admittedly, I may not have learned to get the optimal pitch yet – another fiddle in itself.)
The Rainbow really isn't a single-pole tent; calling it a "strut" doesn't change the fact that it's a pole across the top of the tent. This strut causes me a minor issue in that it forces me to change the way I pack. The strut is best left in the tent (it will come out, but removing it and replacing it is a recurring fiddle in itself.) This forces you to roll the tent around the strut, and the strut is long enough that you are forced to put the tent vertically into the tent. (My Hubba, in two stuff sacks to separate a potentially wet fly from a relatively dry body – oh, wait, can't do that with the Rainbow, either – let me pack the tent itself horizontally, and the poles vertically in a corner.) I've figured out how to repack accordingly, but getting the side-to-side balance just right is now a little more fiddly.
I've read that others find the floor slippery when you use it with a self-inflating pad (there are various solutions to this hassle), but I had no trouble at all with my closed-cell Z-Rest staying put – and I purposely pitched the tent on an incline to test that.
Having said that, there is an incredibly luxurious amount of room – both floor space and headroom – in this tent. Also, in the brief nap I took in the backyard, I didn't get any feeling of stuffiness or any condensation while in it – and I did close the vestibule. The weight savings cannot be ignored. While it wasn't love at first sight, I'm sufficiently impressed by the advantages of this tent to see if I can live with the larger fiddle factor. I'm anxious to take it out on the trail and see.
Why is fiddle factor so important to me? I enjoy my trips most when the maintenance activities fade into the background and become semi-conscious actions. The Hubba tent, and other slightly heavier gear I've been using, did exactly that. My own personal criteria, not based on the objective merits of the SL1 and Rainbow, will make my determining factor how far into the foreground their fiddle factors bring them.
