couch, Luxilon will have a 15 gauge 4G string. I believe I heard it would be released in January 2013.
You are going thru the strings fairly quick, and I suspected this would happen at higher tensions. In my case, I've been stringing at 45, so makes sense I'm getting more durability.
I could try stringing a little lower but I think 55 would be the lowest I'd be willing to try in this racquet. That's not too much of a difference. When I get a couple of these I will have the luxury to experiment a little more with tension but I think the 15g may be the best option for me at this point.