I originally repowered mine and was a little unsure because of the speed, but now with the high gas prices I have grown to love the engine. It does not have the same kick as a two stroke but hey...who cares so long as it's reliable and efficient...I have not had a problem with the engine. Mine is actually a suzuki 140 with the white johnson paint and decals on it, otherwise it's identical. I agree with the above posts in terms of performance -- I get anywheres between 4 to 5 miles to the gallon depending on sea conditions and I have done numerous shark and offshore wreck fishing trips on my boat without a problem.
If I ever had to re-power I may go to the suzuki 175, but the 140 is fine otherwise.
check out
http://www.edsmarinesuperstore.com/
it's where I got my engine and they have great prices on suzuki and it's also a 2% sales tax