Second thoughts: It seems reasonable that liquid will transfer heat faster than gas, which would be a win for poaching. On the other hand, it's necessary to heat a larger volume of liquid to get the process started, so that's a countervailing factor.

I have this sort of steamer-- interleaved pieces of metal which are somewhat difficult to clean, so I don't use it much.

Now I'm looking at a microwave steamer, a flat metal steamer that fits in a pot, and bamboo steamers.