So, I decided to buy someone's used poncho. I am going to practice setting it up as a tarp tent in my yard and hopefully on some overnight trips, too.
I have a large tarp that weighs as much as my The One tent, so I can't see any advantage to bringing my large tarp just for myself. It's only a plus when Tony will be there and we need to sleep two under it.
I couldn't see any advantage to using a poncho tarp instead of The One, either. The One is well-built, comfortable, spacious, easy to set up, and keeps me dry and warm. But for a mere $35 I can at least have a little fun with a poncho.
The poncho system has some advantages over a tent. It appeals to me to have the option of either having roof or not, adding a bivy (for rain or added warmth) or not, using the bivy without the sleeping bag when it's hot (I remember some really hot nights when even having the bag next to me was uncomfortable) and using the bug net without any of the other items when conditions fit. It is hard to justify carring two shelter systems when one or the other will do. So I kind of see this as having to decide between a system with many options vs. a system with fewer options.
Fun with my gear is part of what I enjoy about hiking anyway. A friend was telling me about a trip where everyone carried some of the cooking gear and food, but the trip leader did all the cooking. I would rather play with my own stove than have someone do my cooking.
So even though I really love my The One, I think it will be fun to play with this other system, too. We'll see what I end up liking the best after giving all this a try.