Hi John (and Buddy too [Linked Image] )
This is all good advise concerning 12 strings.......The only make I know of that you can confidently keep tuned up is the Richenbacher models...something to do with the design of the truss rod.....keeping your guit in D will extend the life of your guitar tremendously....I also use the lightest gauge strings that I can find for my Epiphone as you do...you can mix and match gauges if you feel a particular string is "tinny" sounding....could get expensive though...ya know? [Linked Image]......My Epi is 30 years old and still plays nice.....ya just gotta be aware....I have tuned it up on occasion to record.....did not seem to hurt it none....back to D though before it goes into the case....always...

Take good care my friend,
Joe (aka joro [Linked Image] )