I, too, was wondering why a pristine 2004 would already have been re-powered. So that mystery is solved.
I bought a 2002 with a carbed engine (Yamaha). I wasn't seeking out a carbed engine, but the boat was just what I wanted in most other ways, and the price was such that I could stash away a "re-power" fund for future use, so I bought it. Who knows, maybe that new-90-that's-the-weight-of-a-70 will come out in the meantime
I actually went into the deal sort of "assuming" I would re-power, actually. The motor didn't run well (only had 50 hours on it, so obviously not a lot of use) and I went into the Yamaha dealer in a "please show me your new engines" frame of mind. They (politely) laughed at me, assuring me that there were most likely many, many hours of life left in my engine. They basically ended up saying, "Look, let us tune up and service this engine and then you give it a whirl; if you are not happy with it after that, come trade it in on a new one - always better to sell or trade a well-running engine anyway."
Now, if the price of my boat (or "your" boat) had been the same as the price of one with a newer, injected engine? Well then no, of course not. But mine wasn't (and yours isn't either, from what I can tell, presuming the boat is in the condition stated). So to me it comes down to will you be happy with it? Or will you always feel sort of "ripped" and like you really wanted the injected engine. That is the one difference here: You went into being advertised as a 2008 engine, which would be injected. If you add the price of a re-power to the purchase price, how does it stack up? Somewhere in those factors is a guideline for what to do.
The 16 amp alternator might be an issue, depending on how you run the boat (mine also has a smaller alternator, although I think it's 20 amps). On the other hand, the spread might not be quite as bad as it looks because I think the injected engines use more of those amps to run than the carbed ones do (?). I'm sure the advantage there still goes to the newer engines though.
I've drained the carbs on my Yamaha each time I left it for very long (and I try to leave it with non-ethanol fuel onboard). It's a minor hassle but I don't consider it too big a deal simply because putting the boat away entails all kinds of details and procedures and it's just one more. What I mean is, it's not like I'd just walk away from an injected-engine boat -- there would be many steps I'd take to put that one to bed properly as well, just minus draining the carbs.
One last thing is that it depends on what type of boat owner/shopper you are. I purposely looked for a boat that was as untouched/un-used/un-accessorized as possible. That's because I like to choose my own systems, and then install them my way. I'd rather do that than pay for someone else's used systems and live with their installations, things they put on the bulkheads, etc. OTOH, that takes time and energy (and/or money), so it's not for everyone. But for me, for example, I knew if there were trim tabs on the boat, I'd have to "uninstall them" and then prep the transom core the way I like to, and then re-install them. Given that, I preferred not to pay for them in the price of the boat, and then order brand new ones of just the type I wanted and install them. But everyone is different that way.
I think I may have rambled a bit... I blame the fact that I'm spending the day in a waiting room (erm... I mean "customer lounge") while some vehicle maintenance is being taken care of.
Sunbeam
