I work for a company that uses heavy steel plates in its construction. I've been tempted to cut a 1-spoke wheel from 1.5" thick plate and then have it machined to fit a tire just to prove it can be done.

Anyway, from an engineering standpoint, the performance of a wheel is not controlled by number of spokes or rim type or proper tension or lacing pattern or hub details or spoke size or type, but rather by a combination of all those factors. If you're on the upper end of the weight scale and having problems, it would make sense to upgrade somewhat in each aspect, but there's not any one factor that's going to be a magic fix.

To give you an idea- on my Raleigh Sojourn, the rear rim gave out after about 4400 miles. It was a 32-spoke rim. Raleigh sent out a whole new wheel, of a different style, which I think the bike store guy said was used on one of their commuter bikes. Anyway, that was a 36-spoke wheel rather than 32 spokes, so in that respect, it was an upgrade. That wheel lasted 500 miles. So just the spoke count by itself wasn't much of an indicator. And that was with me at 220-240 lbs, by the way.

A while back, I was at a bike rally, and a couple there on a tandem had low-spoke-count wheels. I think the guy said they were Shimano "Sweet 16" wheels or something of the sort. He looked to be maybe 200 lbs, wife maybe 140 or so- neither was "large", but still, combined, they were putting a fair bit of load on that wheel and seemed to be doing okay. And then a while back I was at a bike shop, and they had a tandem in for service that had 48-spoke rims, which I didn't know existed (evidently, they're a tandem-specific thing). From what they said, that couple had had a lot of wheel problems in the past, and those wheels were their ultimate solution to the issue.