I decided to try them out after determining that I wouldn't be able to find latex tubes for my Compass 32mm tires. One of the two Tubolitos that I bought had a defect out of the box where air slowly leaked out from the base of the valve stem, so after a few days (where I had to pump an unreasonable amount of air in each day) I removed it, and was refunded for it by the retailer. I confirmed the leak in the sink with water.
The other Tubolito is still in my rear tire, and it's got around 750 miles on it so far. No flats, but I don't get a lot of flats with butyl tires either, so that doesn't mean much.
It's definitely light, and I believe the thermoplastic they make these from absorbs less energy during flexing than butyl tires do. All in all riding with the Tubolitos in both tires felt very, very much like riding latex, which I've done in the past with narrower tires. Yes, these were expensive, but if they last a long time and are more resistant to flats I think it may even out in the wash. The lighter weight at the rim and lack of energy loss due to flexing, with the very latex-like road feel, I think, are nice.
I'll go ahead and order a new one and put it back in my front wheel. I think I'll ride these until and unless something happens. If nothing ever happens then they were a good deal, and if it does, then at least I'll learn something. I do think these may be a more durable alternative to latex, and for folks riding wider tires like me (32mm, and possibly soon switching to 35mm), may be the only way to get a latex-like road feel. They do seem to be far, far less fragile than latex.