Agreed, but luckily for me, they don't need to carry a whole lot of current. Any tranny that can handle 5A (to be safe) will work just fine.
I'm looking at a few possibilities, and yours is definitely one of them. Another is a LM339 based design, since I actually have 4 separate points that need to be monitored. Easy to set up the brain on a relatively small perf board with the threshold/hysteresis pots, and farm out the trannies to another board or boards.
The big thing is that they have almost no "operating" current. Efficient as possible is the primary concern. So that rules out things like standard relays. SSR maybe, but voltage drop is a concern on a couple of these. The P channel MOSFET is also the best method I've come up with so far as well, since I can also easily "slave" them to control more than one point in the system from a single LVD controller.
Any ideas/thoughts/caveats that anybody has are of course greatly appreciated.