Freeing it from the mold was a bit painstaking (you tug here or there, it still doesn't move, then you go hunting for that tiny bit of putty that's still holding it down), but patience won out in the end. The float half looks good, in my inexperienced opinion, although there are one or two planks in the middle where I can tell they weren't quite flush to the the keel. A little putty will fix that right up later.
The exterior of the float half looked really good too:
I wish I had a better place to store it, but for now the ground floor of my tent will have to do - it's now waiting patiently beneath the hanging float decks. I blocked it up so there shouldn't be too much stress on it. When I get to the main hull, I will have to store the first hull half outside on sawhorses, covered with a tarp, but I didn't want to have to do that for the floats.
I noticed that the keel foam looks bowed (between bulkheads) after pulling it out of the mold. However I've heard other builders report that this is normal and that it will simply be forced back into shape when joining the float halves.
After popping the float half out, I spent some time cleaning up the tent and preparing the mold for the second float half. I got the keel foam glued into place and pulled some foam sheets off the pile to get ready for planking tomorrow. I'm going to plank this float half with the deck flange mold plate off the mold, like other builders have done. Hopefully that will help things go faster.