I firmly believe and agree as Striped Bass has put it that if you’re going 100 mi off shore then you should buy twins. However, I will add that if you’re going 100 miles off shore you’re out over night and this is not the boat for that application. I also think that if you want twins because you like the ouh – ouh manliness of two engines you absolutely should buy twins. You need to really be satisfied with your purchase, nothing is worse than looking at the boat after a year and saying I should have …..
On reliability, I have had boats for a long time (several thousand engine hours) and have never once had a failure. I have a lots of boat head friends we all take very good care of our engines and all agree that the overwhelming majority (perhaps over 95%) of engine failures are operator induced. Lack of attention to operational signs of a pending problem, no or bad service and so on. Gas related problems are next on the list and are perhaps the most common. If you get a load of bad gas it matters not anyway what power option you have as it isn't going to run period.
As for handling, I never even sea trialed the 275 with twins as I just do not want the head ach of two engines, one is more than enough in my book. The 275 handled at low speed like a dream, at idle speed you point the bow and it goes there quickly, almost on its axis. It tracked well below planning speed and did not wander too much. In reverse the boat actually backs down reasonably well. I fly fish and hence have the bow up into rocks all the time therefore handling was a real concern for me as well. Long story short on my sea trial I worked her bow slowly to within ten - fifteen feet off of a rock pile that I know well and worked her for position. Short of the dealer getting anxious about sticking his $100 K boat up next to a pile of rocks she did beautifully. By the way the boat tracked well with no power as well, position the engine to resist the wind and she stayed pointed up pretty well and for a longer period than I would have expected given her windage.
As for the engine in general, with the three year warranty extension now out on the F350 you have six years on Yamaha's nickel at no extra cost. With the F350 you also get all of the latest technology such as variable rate valve timing, fly by wire controls, an over built lower unit.... In my case the twin 150's were ca $3,000 more, that's 3K more for lower gas mileage, lower performance, older technology, more drag, twice the service and less stern space but I’m not bias of course.
Buy what makes you happy, I would not mental m too much over the handling issues or the newness of the engine.
Do any of you know how to post photos, I have the Raymarine C120 installation photos to post but have no clue as to how?