My experience was the same as yours Tim... UNTIL, I watched and talked to the guy we paid to do our hull. The "trick" is VOLUME! I tried to use the right amount of 3M rubbing compound based on the way I interpreted the label. It was WAY too little. However, when I asked the guy what I was doing wrong, he took my Mikita buffer, turned over the lamb's wool pad and dumped a surprising amount of compound in it, handed it back to me and said, "There, that'll do about this much." Pointing to a section about 24"x24". Do small-ish areas at a time. He also told me that you REALLY have to try hard to burn through gelcoat. Yes, you need to generally keep the tool moving, but unless you turn your buffer up on edge and let it sit for 30 seconds, you won't burn through it. The point being, the more you buff - the more shine it takes. Finally, keep AWAY from stainless! That stuff loses it's coating fast and then gray goop gets spread all over the surface you are working on.
With this new info, I went to it... And I'll be dad-gum... He was right! I was really able to get a HEAVILY oxidized surface (the side of the flybridge) to absolutely shine. I bought a gallon of 3M compound for $75 and a spur thingy and I am ready once it warms up some. HOWEVER... be warned that it makes a HUGE mess. The stuff get flung everywhere, so be ready.
Wax to taste and move on.
Anyway, hope this helps.