Ive had
boats with both bolt on fittings and obviously weldments.
Personally Id go for welds every time, and I would echo what others have said, if you're a good welder, break a leg,if not all you will do it create a mess. ( a weak mess to boot).
The fittings rant are not as bad as some would make out, but it all depends on the design, the corners can't take much horizontal movement and any movement tends to exacerbate the problem, Often the issue is that the clamping grub screws arnt great. Personally Id drill them out and thru bolt them
dave