MacGregorSailors.com

What's your boat's name? The admiral and I are planning on visiting the area this summer (possible retirement location), and I'll be on the lookout for your Endeavourcat 30. I may even drag the with us.

A similar sized catamaran may be a good retirement boat for us, or something like the C-Dory, as mobility is starting to become less easy. But the big decks of a cat are power boat-ish enough to maybe fit the bill.

"Those old Yanmar D27 and D36 diesel outboards are loud and a little smokey"

Noisy is normal, smokey is not. I think it's a blessing the motor seized up. I'm telling you, it's a weird motor. IF.. it were maintained it wouldn't smoke and wouldn't leak. However you still have all those non Yanmar standard parts like gears and transmission that wear out and finding parts would be difficult.
The dual modern outboard idea makes more sense. Just be aware that gasoline is dangerous and as such requires more caution than on the Mac. Blowers etc.

The real lesson here is DIY. Whenever possible, do it yourself. That includes all boat related stuff. A "captain" bought our old house. Weird guy and doesn't surprise me you had 2 losers. I can't imagine what you paid these clowns for the privilege of wrecking your boat. The ICW aint' rocket science.
Boatyards are typically seasonal work and they hire seasonal workers. I've seen so many do shoddy work or even charge and not do the work at all, like winterizing. DIY

Cats are a great boat for folks looking for a stable roomy boat. Few can go down the road though.

--Russ