I have not been to the operation in the Keys (we recently moved to Ft. Pierce Fl (about 50 miles north of your Plan B) but have dove the Keys a number of times. They also have a satellite operation in Bonaire just out from the Buddy Dive resort where they are raising stagehorn on the "trees" pictured in their website. Bonaire was hit a number of years ago with a hurricane that destroyed a lot of stagehorn coral beds in the shallows (5-15 ft) which I assume is the driver for their restoration efforts. We first learned about it from a briefing at Buddy either by the dive staff or by Ned and Anna DeLoach (Divers’s guide to Florida, Reef series (editor), Reef Fish Behavior" and DAN contributors) by one of the outstanding briefings on reef life. Overall a very worthwhile project and one of the environmental issues that anyone can help.
On a side note the DeLoachs are normally at Buddy Dive in Bonaire in late Aug - early Sept, the briefings are free and I do not believe they are limited to those staying at Buddy Dive. So if you happen to be their during that time frame (coral spawning season) I would not miss it.