Went pretty well, I changed the thermostat and O-ring while I had the system drained (had a couple of small leaks when really really cold outside this winter that I solved by tightening down the housing bolts a little more that I wanted to take care of). However, both times when I filled it with water (without the thermostat in) it wouldn't take more than 2/3rds or so of a gallon of water. Also, when draining it, quite a lot would not come out until I removed the thermostat housing. On final fill of the system including reservoir, I still have about a quart left in the bottle. Now, I haven't taken it for the final ride yet to try to fully bleed down the system, but is this normal? I did run it for about 4 or 5 minutes, but the level didn't seem to go down (and this happened on all the water flushes as well).
Whenever I have refilled after draining and run the engine for a while I have had to only add a couple of oz. I would think you would be OK counting on the reserve tank for makeup. Just make sure that you fill at the cap under the tank.