not really - the problem is the spinnaker halyard loads up above where the stays connect and where the mast is unsupported by anything other than the mainsail. The only way to fix would be to support the mast up higher by using baby stays or something - really wouldn't be that hard to do.
I was wondering if the change in the angle would change the loading on that part of the mast, but that is for you engineering types <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" /> .
I guess with the apparent wind running the show all the time on cats the mainsail should be tight anyway, right? I guess it would be more for the "gonzo" days and to protect the mast (esp for those people who have really expensive masts I guess). Like you said though, doesn't seem like it would be that hard to do. Most high end monos have running backstays that would work, in theory, on cats (aside from getting in the way).
