If, like me, you use your motor to get you home on schedule when the wind dies or is coming in on the nose, I would say go for the 9.9.
I've got a 4 stroke Yamaha 9.9 High Thrust on my 25 footer (about 2200kg). I purchased it second hand (one half of an ex catamaran setup) and have been really happy with it. At the time I was tossing up between the Tohatsu (Nissan), Honda and Yamaha and was actually just about to plonk the money down on a new Yammie when I came across this not too old used one. It replaced an 8 hp two stroke mariner.
A bit of Internet research made me favour the Yamaha High Thrust as it has both a good reputation and is designed especially for displacement speeds - even down to the extra reduction in the gearbox. The Honda has a high thrust prop option, but the gearbox is the same as the standard model. One thing I liked with the Honda is that it retains the pull starter whereas if you get a flat battery with the Yamaha, you have to remove screws to get a rope on the flywheel pulley to start it by hand. The Tohatsus are well priced and light weight but I know of people that have had some issues with corrosion of some mild steel components on them in moored / docked situations
Anyway, love the Yammie. Rarely need to run it at anything past 1/3rd to half throttle to get up to about 5kn+ on my boat, reverse works exceptionally well (something that didn't on the the old Mariner!). I don't normally use the motor in a blow, but I've used it to push against a 4knot current when I've been in a hurry and it'll push the boat well up onto the bow wave at near full throttle.
Fuel usage is about two litres an hour at 5 to 6 knots which is a lot better then the old two stroke it replaced.