Another Rochesterian here.
I started out five years ago on a hybrid. They are perfectly serviceable bikes for commuting. I put 4,000 commuting miles on mine before I switched to a road bike.
The "thinner" tires on hybrids are just fine. You won't need fat MTB tires even on the gravel parts of the canal path. Even most skinny road bike tires are just fine on the gravel parts of the canal path.
Speaking as someone whose primary commuter has disc brakes (an '06 Trek Portland), unless you intend to ride regularly in the rain and snow, disc brakes just add unnecessary cost and weight. I haven't missed a commuting day since July 2006, so they make sense for me, and I wouldn't have it any other way. But for most folks, traditional rim brakes are just fine and you can spend the savings on other accessories.
You were looking at the FX 7.3 Disc.
The FX 7.1 is $450. A lot of that difference between them is in the brakes.
The FX isn't a bad bike for commuting. Its wear parts are inexpensive, it has front and rear rack mounts and it take fenders easily. I would lean towards
the 7.2 at $550 for the component upgrades and puncture-resistant tires. Flats are not fun on the way to work.
Towpath Bike is a decent shop. I've had good experience there, and most of the staff are year-round employees, which is good.
You'll also want to visit
Park Ave Bike. They're equally reputable, but employ some seasonal sales staff, which is sometimes hard on a newbie. I like working with Sam (Samantha) at the Cover St store.
If you live near Pittsford and commute 12 miles one-way, that puts you near the University or downtown, right?
Visit Freewheelers on Mt. Hope between the medical center and 390. The guy is a little quirky, but he's an excellent mechanic and fair businessman. A large percentage of his business comes from the University.
On South Ave near Gregory St is
Full Moon Vista Bike & Sport. As with Towpath, most of their staff are year 'round employees, which makes a world of difference. Better still, they know commuters and commuting.
Hope this helps!
Craigslist around here is mainly MTBs, BMX and POSs that have been rusting in people's garages for 25 years.