Today I did some A/B testing with Hertel Hot Sauce (thanks for the sample Randy!) and One Ball Jay Summer Slush wax (thanks for the tip boardski!).
I put fresh wax on two boars last night, scraped and brushed. I took a few runs on my Donek AX with the Hertel wax and while most of the mountain was pretty fast (much faster than I expected given the high temps and clear skies), there were some definite slow spots, particularly in an un-groomed area that I pass through on every run (the face between the upper and lower terrain parks at Summit Central, for you locals). This area gave the "brakes on" feeling I referred to in my first post above.
Then switched to my Donek FC, with the OBJ wax, and did the same runs. Mostly it felt pretty similar, maybe a tad faster but not significantly, however in the ungroomed section, the "brakes" sensation was pretty much gone. I took a few runs to confirm. Occasionally I could feel just a slight hint of braking, but mostly that ungroomed section felt just as fast as regular snow.
I switched back to my Hertel-waxed AX again to double-check / confirm that it was the wax and not just changing snow conditions, and the ungroomed stuff still felt really slow. The brakes were still on.
The AX has a slightly more ungroomed-friendly nose, is .5cm narrower, and has a base that is structured for wet snow. All of that should have been to its advantage today - if it had been the faster board I would need to try again with the waxes reversed. But the OBJ-waxed FC did much better in spite of its minimal structure and flatter nose. The FC is a few cm longer (180 vs 172 for the AX) but the improvement was way more than the few percent that difference alone might account for. The boards have almost identical flex.
So I declare One Ball Jay the winner, by a large margin. Plus it smells really nice, like fruits or berries or something. My girlfriend said it smelled like I was making pie. :) I find it strange that OBJ is targeting the same people who buy scented candles, but I'm OK with that.
I'll order some of the other suggested waxes and try them out next spring.