First of all, don't vent it out the soffit. The moist air will just get pulled right back into the attic thru the soffit vents. Obviously, many here are trying to have you avoid the attic all together, and if you agree, the soffit venting idea mitigates that. Having said that, I'm not a "sky is falling" type when it comes to attic venting and mold. I presently live in a house built in 1954 and my master fan goes straight to the attic. Judging by the fans' construction and the jet plane noise it makes when I turn it on, it's been there since day one. There is not one hint of moisture or mold in that attic. I know the signs of mold, and there are zip, zero, zilch, nada...get the picture :) Here's what I would do. Send the president of the association an email confirming his "...that's what everyone does..." statement. When he responds, print it out and throw it in a file you'll never lose. Now go ahead and vent that puppy straight up to the attic and forget about it. If the you know what ever hits the you know where, you simply pull out your never lose file and smile.

This is great feedback, thank you all. Olychick, you should know that when my bride saw your first post, she said,"Olychick has clinched it for me - we'll have Fantechs, and the builder can figure out how." :-) We may wind up using a single out-the-wall external fan for the downstairs master bathroom, but she was really keen on the dual grille/single inline fan system (one grille over the shower, one in the commode closet). Funny thing is the downstairs powder room is dinky, but has an unobstructed pathway up through the ceiling/attic/roof, so we could use whatever we want for that - same for the upstairs Jack 'n Jill bathroom. Sigh.

You probably figured this out by now, but I just completed this nasty little project today myself. At first I bought the wrong fan, got home and realized that our 40-year-old fan was an axial fan which mated directly to 7" round ducting, straight up, through the roof. Since access to the crawlspace would've been a huge hassle (to try and make a centrifugal fan work instead, as suggested above), I went back to Home Depot and bought an $87 NuTone axial fan (it's a "NuTone 8210 8" Vertical Discharge Utility Fan"). Although it's called an 8" fan, it actually has a 7" outlet (so it mates with 7" round ducting). The darn thing sure is loud at 6.5 somes, and very utilitarian in appearance. But it sure sucks out air at a pretty good clip: 210CFM. I actually like its utilitarian aesthetic and it works quite well with our "industrial-tech" motif, but I would've much preferred to install a quieter Panasonic fan instead (don't think they make axial-mount fans). Anyway, bought some 7" ducting, and went at it. This was a tremendous hassle, with a PITA factor of about a million. Finally got it in and wired. Anyway, the moral is . . . they do make axial fans that should be a near- direct fit to your existing cavity and ducting.

Ideally, I'd have the heater on a programmable timer. It'd run from about 15-20 min before we got up during the week for about 30 min (you can also turn it off manually when you're done in the room). I had one of the Intermatic programmable switches, but it was kind of poorly made. And my wife's an ultra light sleeper, so she'd fuss if the heat came on in the bathroom and woke her up. Now it's just a manual switch. The point is that with our high ceilings, it takes a while for the WW to make a difference in the temp in the room. The heater is on one side, and it has a diffuser to give you a little flexibility in which direction it blows (pretty much either down or down/along the long dimension on that side). Remember that air blowing on you while you're wet in winter (dry air) is going to have to be pretty warm to feel warmer than the heat you lose by water evaporating off your skin. For us, the heater mostly makes the bathroom more comfortable for after you get out of the shower. But, if your ceilings are lower, you'll notice it quicker. As for running the exhaust, when I'm totally done in the bathroom, I switch off the heat and push the 10 min button on the Leviton timer switch for the exhaust fan, open the shower door (so the shower will dry out during the day), turn off the light, and I'm gone out the door. I'd start it earlier, but the munchkin likes to close the shower door, and I'm afraid she'll manage to break something by slamming it against the fixed panel.