Whats the biggest tire size you plan on running?
If I was to stay with 37s, I'd get the D44 and upgrade them as needed/funds allow it. I wouldn't put 1100-1200$ in shafts and locker on a D30 and I wouldn't spend money on D60. You won't break JK D44 with 37s on a 2doors.
2300$ for rubi D44 is a really good price. So if one day you decide to go one-tons, you'll be able to sell both D44 for the price you paid. You won't lose money with that. As for your D30/D44, if you were to sell them, even with shafts and a locker in the 30 you won't even get what you paid for the shafts.
P.S.: If you decide to go with rubi D44, keep your D30/D44. If you get in an accident with your JK and the insurance co decide to scrap it, you'll be able to get your D44 back and put the 30/44 under the jeep before it goes to the scrapyard.
'09 JK Unlimited Rubicon