I was running a Mercury 15 on our aerotec 380, liked the idea of trying a 25, but had to be cheap at the time. Going from 36kg to 50/55kg seamed a bit of a jump, but had a look. Came a cross a Johnson 30hp,,, mid 80s through prop so could only be from 84 onwards. 20-35hp all the same weight. When I first saw it,,, it was a no no,,, it looked huge and at 52/53kg thought no. When back 2 days later and bought it,,,, its great fun.
So ran either the 15 or 30 for a year or two, but needed some space and cash so sold the 15,,, have not missed it. That was shimmed up 25mm and the Johnson 50mm.
Have since bought an nearly new tohatsu 25 2stroke (51kg), so the Johnson is going. If we are going some where new to launch, I find out as much info on the site as poss. With using launch wheels on the boat as long as its not mega steep we have no problems. The most awkward part with the engine is the lifting in and out of the boot. I now have the shim down to 40mm and have no problems with the water over flow.