I have some experience with the 20HP Tohatsu.
Not a bad motor. Kind of simple. Kind of cheesy, in my opinion. Made by Nissan. Nissan, Tohatsu, Mercury all are the exact same motor-difference being the paint and stickers. They're identical. The 15 and 20 are the same powerhead, IIRC. Carb is different. Best of my knowledge, nothing else changed other than carbs. Gearcase is noisy. Kind of rough running, IMO, for a 4 stroke but I'm used to Yamaha's and they are a much more refined outboard-but also much more expensive.
I've run the Tohatsu quite a bit over the last 9-10 months. It runs fine. Once it was tough to start initially but it sat for about 2 weeks without being run and the fuel was probably starting to go south. Once it was running it was fine all day long. The river we use it on exclusively is VERY quiet so you can hear noises from a mile away. That noisy gearcase can literally be heard a long way out even just idling in gear. In neutral it's quite audible. In gear it's noisier yet. Annoying at certain engine speeds, say 2000-3000 RPM and then again at about 4000-ish. At slow idle it's not harsh but still annoying.
https://s262.photobucket.com/albums/ii94/toddh687/?action=view¤t=IMG_0582.mp4
It does have power tilt which is NICE! And it didn't cost that much more to get it that way. Well worth it. The only thing I don't like about the tilt is that it's not trim. It will not tilt while under way with any throttle input other than idle and VERY low RPM/load.
The extra weight of the 4 stroke is definitely worth it. It can be offset somewhat by carrying less fuel. With the 4 stroke, I don't carry much more than a couple gallons. I have a 3 gal tank and it will easily last me all day long even running the river. I also carry a smaller battery. Don't need that great big grp 27 battery that weighs 65 lbs. I just carry a red top optima which is 39 lbs.
