David, did you mean to say you'd prefer 6.2's?
The 330EC/340AJ were beamy boats with straight-shaft inboards, so the additional weight and size of bigger/heavier engines isn't much of an issue.
The cabins are nicely laid out and feel roomy, but I agree with David that with the engines occupying the space where you'd have a mid-cabin berth in a Sundancer, sleeping quarters are compromised.
These boats attempted to split the gap between being a family cruiser and being fishing-friendly. They probably did so as well as possible. Compromises on the cruising side include no mid-cabin and less lounging accomodations in the cockpit. I've never fished one, but at a glance, there are issues like a swim platform getting in the way, a lack of pole storage and mounting options, and a lot of "pretty" stuff that you wouldn't necessarily want to spill fish guts on.
It's a bit of a niche boat, but it might fit the bill perfectly if you're not expecting double staterooms or a serious fish-guts battle wagon.
They're well-respected around here, which BTW is where your subject boat is located. If you get serious about this boat, I might be able to swing by and take a look and snap some pictures...
As far as the demise of the design goes, I'd guess that it had more to do with the niche being smaller than SeaRay wanted it to be. I know of no handling or construction issues that would explain the discontinuation of that line.