It's the BJCP's guidelines vs. the BA's GABF guidelines. So 3 different organizations. I don't know anyone using the GABF guidelines in the homebrewing world mostly because they'd be crazy impractical and they are very tuned to the needs of that competition and audience. (e.g. they need to respond quickly to trends in the commercial market to allow brewers to enter and be rewarded)
That's one of the dirty little secrets of the whole guidelines business, they're not just an exercise in taxonomical purity. Ultimately, whatever guidelines you use need to be balanced for the entry patterns you see to ease judging overload.
One of the more obnoxious trends in the Falcons is that we've always maintained our own guidelines. i haven't put the newest revision online yet, but here is the last one - 2010 Falcons Style Guidelines
One of the things I was happy to see is that we already cover a number of Thomas's findings in the guidelines. (Ok, I needed to do it - so here are the 2012 Guidelines
with its one change)
Belgian Blonde Ale
Belgian-Style "Wild Ales" (this is our catch-all for things like Temptation, etc)
Two Saison categories
And like Thomas, we discovered most of these via watching our entry patterns. Years ago, we had to slide our categories around to make things make more sense competition wise - e.g. APA became it's own category since we had a huge overload of APA's. We moved DIPA into the Barleywine / Old Ale category to put it on even footing instead of in position to blow away regular IPAs.
We still have to split up our specialty categories better to reduce burden and to also allow for more entry configurations for the Doug King Memorial Competition, but small changes are good.