Hey, Jon,
Congratz on the new MK. Play her in good health! I've had my new Signature for a month now, and I sent Mica DR Hi-Beam 45-125's to put on it from the mothership. They play and sound awesome, and IMHO, they would be just fine on your new MK. You don't need anything lighter. The Alembics play great anyway, and the DR's just add to that. If you look in the archives, there are a mind-boggling number of posts on string choices. If ya have a couple days to kill, look some of them up. Interesting reading and opinions...
Have fun, Mike, tho.....