I had the same motor on my first RIB - as the wizzos on here have said, its a very abrubt jump from 2 to 4, quite weird to handle and a pain in speed restricted areas.
I had trouble with freezing carbs in the winter trips to Tobermory (solved by the addition of a mercury 'cold weather kit' ---- a small selection of pipes and tees to route water round the carbs I recollect)
The bottom carb also seemed to attract salt(water) and give issues and I really dont think the 2+2 made any great difference on economy. Quite a thirsty beast and temperamental to start /flood compared to the newer outboards. Swapped it for an Opti
I wouldnt opt for one unless its the best/only option you have
The one 'advantage' is of course - 'simple' to work on with no electronics