I agree that a two-person tent is lighter than two singles. My buddies and I prefer to take two solo tents because we don't always stay together. Sometimes, one of us will be in the mood to camp by the stream, and listen to the waterfall; the other will go up the ridge, because there's a better view of the stars. Occasionally, we'll even separate during the day to do a side trip or explore a different trail, then meet up at night.

But that's just us, and we agreed up front that we weren't really hiking as partners. My son and I have taken a couple of trips as partners, made the agreement up front to stay together, and used his two-person tent (and split other gear), and it did save us several pounds.

The important thing, to me, if you're splitting gear is to make the decision to stay together up front, and be able to trust the other person to stick to it. The second most important is not to get locked into gender stereotypes when splitting the load.