After a few months of using our Leisure Furl boom, I can give a report of first-hand experience. We like it very much. For us, it simplifies sailing makes it considerable safer. I cannot speak about other manufacturers or even other installations of the same product, but for us, it works.
Usage is fairly straightforward, though there is an adjustment period. We raise the main by use of the powered winch on the cabin top of our 40. There are two lines involved, the halyard and the furling line. A slight tension (finger tip, really) must be kept on the furling line as the halyard is on the winch. To lower the main, the process is reversed. The furler is wrapped on the powered winch and tension must be kept on the halyard as the furler moves on the winch. We solved the precise angle of the boom to the mast by determining the 87 degrees and then measuring the distance from the aft grab rail on our dodger top to the bottom of the boom. In our case, it is 20 1/2 inches which we marked on a boat pole with electrical tape. So, once we adjust to that distance, we simply lower the mainsail. The sail cover is built in, so no more climbing on the mast pulpits to attach the old sail cover. It is as simple as standing in front of the mast and pulling on two continuous lines in the boom, and the cover slides in place. My wife made a small cover for the gooseneck to cover the luff. I think it takes 20 or 30 seconds.
Sail adjustment can be made by using the powered winch to flatten the main rather than tightening the boom too much (we have solar panels on our bimini).
In the learning process, I have made a couple of dumb mistakes, and no doubt I will make more. The unit works very well for us. Downside: it was expensive, and we had to have a beautiful new main crafted by our loft. Now our jib and staysail look drab and old.
Quan Yin PS 40 #33