Bruce,
So what exactly is a typical string configuration? The diference in total tension on a strat scale instrument going from a set of .009's to a set of .012's at the same tuning is 78 pounds. Now if we look at some more tensions of the same gauges at different notes we can see that on a .009 gauge set the low E string is a .042 at 14.8 lbs of tension. On a .012 set the same string is used as an A note (up a PERFECT FOURTH) an comes in at 29.3 lbs of tension. Now if we continue with this comparison and assume an approximate tension difference for the high E string (up a fourth to A) of about 10 lbs, then the total difference in tension for tuning UP a fourth would be around 72 lbs. That is around the same differential as going from a set of 9's to a set of 12's (taking the 9 gauge set up a fourth results in about the same tension as just throwing on some 12's at standard tuning. Of course this doesn't take into account a shorter scale (thus lower tension) instrument, or smaller gauge strings. It seems to me that one would have more to worry about in string breakage because of this, and not neck damage. I believe Johnny Marr of The Smiths tuned his guitar up to get a more chimey sort of sound, although I can't remember how far up he tuned it. Now maybe I need a physics lesson as I am extracting my data from D'Addario string packages and perhaps my line of reasoning is flawed, but it seems that people use gauges from .008's to .013's on the same guitars, with little more than a change in setup. I'm still very curious about all this, so maybe some scientific-minded individual can set me straight if I am in error.
peace,
Kip