Length: I sleep curled up in the fetal position, so no problems with length for me. And I'm 5'3". My feet may hang off but that has never bothered me. That's why I didn't want a BA mattress because even their shortest length (60") is longer than I need. For those of you who are tall or who like to stretch out, you'll have to try it for yourselves (maybe a night or two on the floor at home, so you can send it back if it doesn't work). A lot of folks seem to do just fine with a 3/4 pad, maybe with their pack under their lower legs, while others are miserable. If you've used a 3/4 pad successfully before, you should be just fine. If you didn't like a 3/4 pad before, you definitely won't like a 3/4 air matttress. YMMV!

Tubes: I inflate the mattress only about halfway. I therefore have no problem with getting stuck between the tubes or even feeling the space. I do a LOT of turning over, too! The space between the tubes could be a problem if you pump the pad up full. Pumping it up full makes far too hard a surface for me--similar to being directly on the ground! The manufacturer's instructions say to let the air out until the mattress is comfortable. With my Thermarest LE, I would let it self inflate and then, once I lay down, let a little air out of it to make it softer. With the InsulMat, I have maximum comfort when my hip sinks down in until just barely (maybe 1/2-1/3") off the ground. YMMV again!

Weight: The InsulMat Max Thermo on my digital postage scale is 16.8 oz. without the rather heavy stuff sack, which I don't use because I put the mattress in my pack's pad pocket. Evidently the manufacturer rounds down while I round up....