I've purchased 6 or 7 Sena SMH10 units for various friends and family, and they all work pretty well. The batteries are shot on the oldest ones, after ~3 years, they'll only work for 30 minutes on a charge. So I took one apart (easy peasy, 3 screws) and looked at the number on the battery, then found a replacement battery on ebay for around $12, with an upgrade from a 560 mah battery to a 650. It still fits fine as long as it looks like it's shaped the same. Minor amount of soldering to fit the old connector onto the new battery.
I've installed new batteries in 3 units now, and it's great to suddenly be able to go all day with an open intercom and not worry about battery life again.
Of course, we still do the pairing dance at the beginning of the ride. 2 riders is pretty easy, 3 is sometimes tricky, and ONCE we have had 4 riders paired. It's half tech, half black magic. The only thing more fun than that is the Sena device manager and getting it to recognize devices, altho they may have made progress on that. I upgraded a new unit 2 weeks ago, and it was pretty painless.