Well, I unfortunately can't afford a mini Transat or ultimate 20

(nor a 40 footer for that matter), all of which might very well be overkill on Lake Champlain, btw...And I do need accomodations, if not for me, at least for the missus, so I can't get a Melges 24

Of course I can only speak about things in theory here, as i don't have the experience you have, but I took the liberty of comparing PHRF, which, even if not fullproof, seems in general to be a good indicator of speed?
PHRF (straight from USSailing.org)
Beneteau WK: 195
Hunter 212: 216
US 21 (i.e. Pearson Triton 21): 201
Macgregor 26: 228 (not sure if S model would have same rating or lower)
Cal 21: 255
Cal 25: avg 220
J22: 177
So the impression I get here is thin is fast, even if sail plan is not large (j22), unless your boat can plane, then it's the best, but it needs big sail plan and good ballast for stability (mini transat and the like).
Specs:
______________weight______length______sail plan_______Ammenities
Beneteau 235____2500_______23.5________250________Galley,Cl sed head
Hunter 212______1800________21_________213________porta, galley opt
US 21__________1700________21_________224________port a, galley
Macgregor 26S___1850(*)_____26_________234________galley, clsed head
(*) w/out water ballast
Most small boats have higher PHRF ratings than the ones posted above, plus they are often older, have smaller sail plans, so I assume slower, more maintenance, less interesting ammenities, hence limiting my choices to these 4, w/honorable mentions to the Merit 23 and Kirby (22?).
As for speed, well I don't plan on racing anytime soon, or scare the living crap out of my GF at first, but if I can friendly pass other (bigger) sail boats on the lake, that would put a smile on my face. I know the Beneteau can do this, I've been on their fan site, but it seems bigger/heavier than what I feel I need/want. the M 26S looks nice and sleek, but I'm concerned about the boat's sailing abilities and speed (this is not the powersailor model though). The Hunter seems easy to learn/sail while still reasonalbly fast, has a nice big cockpit, and with flat bottom, and option to get a bigger headsail or
spinnaker, seems capable of being far faster IMHO, but interior is limited and since newer is usually expensive. That leaves the US/Pearson 21, which at first glance seems to fit the bill nicely (heard it's very fast), but it is the oldest model of the bunch and they are quite rare...