Since you've done a fair bit of web reading, you may have run across this, but...
Maine Sail is an anal type (sailor who posts on sailing forums) who likes his gelcoat (and likes it shiny

). I had already buffed out a few boats going by word-of-mouth how to at boatyards (pre-Internet), and used what is basically his method with good results. But he is very specific and really puts a fine point on it, if you like that sort of thing (I do!). I changed a few of my compounds and bought a new buffer after reading his how-to.
In Ye Old Days I used to rent a big metal heavy-duty Milwaukee buffer. I never once found a "homeowner" buffer that would touch the job. The Milwaukee did great, but oh my aching shoulders. By the end of the day I swear that thing weighed fifty pounds (and of course I always seem to end up with "lapstrake" boats just for extra joy).
But starting a few years ago, after reading Maine Sail's tutorial, I bought the Makita he recommends. It works as well (or better) than the Milwaukee and is significantly lighter (as least going by memory from the Milwaukee).
Sometimes there isn't enough gelcoat to work with, but most of the time there is (I find that most boats haven't been buffed out over and over - it's too much work!). You can always try in the old "inconspicuous location." Back on my first time, I just wasn't getting it. Friend came over, grabbed the big buffer, and "laid into it" MUCH more than I'd been doing. Voila, shiny!
Note that if you search you can find various versions of this tutorial. Maine Sail participates in a number of forums, and has written about it at various times.
http://www.sailnet.com/forums/gear-main ... h-wax.html