I just put a Northstar F210 unit on my Overnighter. I went with this unit because some people on this site recommended it and it was only $99. I've only had it out on the water once for a brief ride but I can already see that I'll be adjusting my trim and RPMs. The primary reason I wanted a unit like this was to find the optimum trim and cruise RPM.
One thing that surprised me (if I understand the book correctly) is at idle, it says that I'm burning fuel at a rate of over 7 gals an hour. I'm looking forward to a spending a few hours playing with it soon.
Gary 89 Overnighter 200 hp Johnson