I ended up going with UPB (Universal Power Bus) products. There are several vendors, the one I chose is “Simply Automated.” About $70 per single-circuit 120V dimmer switch. So far very reliable, and there is a working OpenHAB binding for UPB. You will also need a $70 UPB --> RS232 controller. (They also make a USB UPB controller, but don’t buy that one. The OpenHAB binding only works with the RS232 version.)
FYI, I am using CREE A19-style LED bulbs on the UPB dimmers. Dimming is very smooth and quite stable, though the bottom end (lowest dim setting) is not quite as low as I’d like it to be. I have also tested power consumption of the bulbs through the UPB dimmer & found no surprises there. A ~20 watt (actual) LED bulb will dim down to about 1.6 watts on the UPB dimmer.
Your mileage may very, I strongly suggest starting out with just one or two UPB dimmers and testing your bulbs carefully before investing a lot.