I have a 14' Coleman Scanoe with a Watersnake 54lb thrust trolling motor on it running off a group 29DC Everstart battery (Wal-Mart). This combination works great for me and my two sons. The canoe has a motor mount on the stern, but the stern is still tapered to a point like the front, so it makes for easy paddling and motoring even in reverse, which is something to consider over a traditional square stern canoe. I put the battery up front behind the front seat, and spliced in a jumper cable wire to reach the motor. Neither the battery nor the cable gets hot, even under prolonged use. I did shorten the motor shaft from 42" down to a more canoe-sized 22" to avoid the gorilla arm posture.
I've only taken it out twice now on local rivers/creeks (NE Florida), but I've already encountered several situations where I wouldn't have wanted a gas engine, just from the noise. On my second time out I encountered a group of four kayaks who were also fishing. I just dropped the trolling motor down to the lowest speed and passed them silently with no more wake than if paddling. I was warned by a marine patrol on a decent sized creek about my wake (no wake zone) when going full speed with this motor, so I would have to say it has plenty of power. Can't vouch for a lesser thrust motor, though.
Each time I went out I was motoring around fairly constantly for about 4 hours (mainly testing the boat/motor rather than fishing), and the battery never went below 85% charge either trip. The battery is rather heavy at around 65lbs, but the battery I chose is probably overkill and you could get by on a smaller, lighter battery. My attitude was that if I'm going to go to all the trouble of having a motor on my canoe, I'm going to use it rather than paddle around the extra weight. For toting the battery around (including portaging), I use a folding wheeled luggage dolly that's rated for 150lbs. Don't worry about looking for a heavy duty one -- even the typical tiny wire one is rated for that much weight and is what I'm suing. Even with a bad back, I can carry the trolling motor and cable in one hand, and pull the battery on the luggage dolly without too much, if any, issue.
Personally, I don't see me buying a gas outboard for my canoe unless I start frequenting larger rivers and lakes, which I don't see me doing in a canoe. I bought the canoe because I wanted to fish smaller waterways, and this combo seems to be doing that perfectly. If I'm going to go to bigger, deeper water, I'm going to get a bigger boat, and probably have both an outboard and trolling motor.