Lol, I know the feeling. And while it's not perfect, it can still be revealing if they have a testing room where you can A/B the two speakers. It can't hurt; just listen to the speakers, not the employees.
I have listened to both monitors, and really love both. I always recommend the HS80ms to people looking in that price range. You can usually get them used for about $350. That said, they aren't perfect; most notably their brightness (upper mids and above) can be fatiguing (the hf roll-off switch does help). My apartment mate has them and loves them.
The Adam A7x
are in a different price range, and I really do love them too. They have all the hf detail of the Yamahas without the sense of bright harshness (to my ears). I find them a pleasure to listen to. If I could afford them, I'd own a pair.
I don't remember much about the low end of the Adams. Certainly wasn't problematic. I know on the Yamahas it's reserved but accurate.
The Dynaudio BM5as are another monitor worth considering, in between those two in price. 6.9" woofers. The low end is a bit bulbous, but still very accurate. Makes your room bump in a pleasant manner :P. I find the highs to be much smoother and more pleasant than the Yamahas. Very detailed up there. That's what I have right now. There also quite compact compared to the Yamahas. I'm very happy, and don't think I'll feel the need to upgrade anytime soon.
Anyways, they are all great monitors. Consider watching craigslist for a while, and seeing what comes up. I got the Dynaudios for the ridiculous price of $400. The Adams don't come up much, but I've often seen HS80ms around.