Since I can't compare a 15+ year old boat with TBI or EFI to my boat, then I'll compare my 98 Jeep with EFI to it...it ran perfect till about 12 years old and 140,000 miles. Then started the random stalling common to older Jeeps. No codes set. You check all the sensors, you check every connection, all the grounds, batt clamps etc first. By a process of elimination you get to the ECU. Now, there is a big debate in Jeep forums about OE vs aftermarket. Consensus is if you want a trouble free install go with OE. So that is what I did. Price from the dealer for the ECU was a bit over 600 US, installed. They have to flash it with their ChryCo supercomuter so you can't really do it yourself like you can on the older pre OBD-II models. . So there you have it, 2x the cost of my carbed boat. And my Jeep has been better than some of them, still on the original fuel pump. Many have had failures of those and they are about 400 at a dealer if you can't do it yourself.
The tune up on my 07 WK Hemi I referred to I did myself. Not really hard, but some wiring and fuse boxes are in the way.
BTW the last carbed car my family owned was a 1975 Olds Delta 88 5.7 4bbl Quadrajet. They had that car till 1989 (14 years) and it never needed a carb rebuild. Just tune ups and an GM HEI module.
I have 9 small engines around my property, lawn maintenance stuff, snow blower generator, etc. Four and two stroke. Some of them are over 20 years old. I've only had to take apart the carbs on the snow blower and the leaf blower, once. To blow out jets and then they ran fine. I have a Briggs 3.5 hp lawn mower that's 27 years old the carb has never been off, never. This is also using E-10 gas which we know attracts moisture.
I don't disagree with you at all that EFI engines are easier to start, run more consistently and need less maintenance. There is no debate about that. Where there is a difference is in ease of repair and parts cost. Sometimes, if the specific parts used in marine EFI systems get discontinued then you are out of luck. That's why I advised the OP not to get the first few years of TBI, simple parts availability.
If you follow threads on
www.thehulltruth.com you will see that the new high tech outboards are not without their problems. Four stroke or high pressure direct injection 2 strokes. These include a greater sensitivity to ethanol fuel (Yamaha especially), random electronic faults and very high parts cost for ECUs and fuel pumps as well as injectors and high pressure pumps on Etecs and Optimaxes. There is no free lunch. High tech is great but you do pay for it sooner or later.
PS I noticed you never commented on the threads I Iinked to problems with Volvo fuel pumps on EFI boats, or the repair cost suffered by a guy in Australia with an EFI Merc. Why is that, is it so hard to admit, that I have a valid point?