There’s this idea in catamaran design that you should “balance” the transversal and lateral stability that seems like it’s not terribly well suited to cruising, for a number of reasons.
Firstly, the ways catamarans capsize (or rock, or heel) isn’t the same forward to back and side to side. Burying a hull in a swell is much worse than blowing over. Moreover, blowing over is quite easy to prevent: don’t run overcanvassed. But burying a hull is a function of your speed versus the wave size (all other things equal). So, for my money, I would much rather give myself the extra LOA, and not have to worry about endo-ing.
Second, your cost goes up dramatically the wider the cat. The strength of the structure is dramatically different. So, to make a bigger cat, rather than making it according to some arbitrary ratio, factor in the cost, and the carrying capacity, and the righting moment.
Third, the people that I can see who actually have the ability to make catamarans to suit themselves, and who actually like to sail them around, tend to go with a longer, narrower cat. Wharram, Bob Orem, and one of the couples who built one of Richard Woods catamarans (that he has as exemplars on his website) actually went through the trouble of lengthening their catamaran. These aren’t people who are looking to break records, not really looking to impress anybody but they do want to do passage making and like moving about in cats much better than monohulls.
Finally, I think it’s potentially a much better solution for getting accommodations in marinas. The limiting factor in most berths for a catamaran is the beam, not the length, and a cat (if it can fit in a berth at all) is going to be taking up all the width, and not much of the length. I think it might be a better idea to design a cat to fit a certain standard berth, rather than something that looks good in press shots but that you have to park way out at some mooring because there isn’t any place wide enough to park (or there is one, but you’re going to pay megayacht prices for).