I have a Soler & Palau 100CFM unit to vent a 5x7 bathroom. The only thing I would do differently is neoprene-mount the fan support. It's much quieter than the cheapo Broan it replaced, but it's not completely silent. I have it on a dimmer so I can slow the fan down, but I don't know if it's worth it or not.
I did cut a hole in the roof and replaced the shingles around the vent. I also used insulated ducting, and anti-reversion valves at both the roof and the ceiling.