Setting aside everything but grind quality; I look at motor power (bigger will usually run cooler), RPM (slower will keep the coffee cooler), burr size (bigger permits lower RPMs), burr carriers (forged usually more stable than stamped - and ALWAYS avoid plastic carriers).
Some grinders are noisier, others are less messy, some run hot to the touch, and some just look better. But generally, I judge grinders by grind quality. If I was in the market for a grinder I'd be looking at used commercial espresso grinders on eBay or Craig's List. In this category I like all of the grinders in the 60 mm range, with my favorites being the Rancilio MD-50 & the Mazzer Super Jolly, and I'd pay no more than $250 (including S&H) plus another $50 for new burrs.
If I insisted on getting a new grinder I'd get a Cunill Tranquilo. I've used them, like them, and highly recommend them. There are other good quality espresso grinder to be had at reasonable prices.
Nice looking machines, and Tom does a great job explaining why clumping is a problem with doserless grinders.
I wonder how the Compak would stack up to a $235 Cunill Tranquilo? 
After you suggested I get rid of my rocky for a more serious espresso grinder, I read about the Cunill tranquilo, the compaq K3 elite( enjoyed SM review) and the Cimbali max hybrid. If you just read the reviews of folks out there using the stuff, I'd rush out and buy the Cimbali max, but it's almost $800 @ Chris. I guess I have the same question you raise above. Is the grind going to be worth it from a machine that is 3X more assuming each machine is reliable?? Has anyone really compared any of these machines head to head? Has anyone in the GCBC had experience with the Cimbali Max hybrid?
