Yeah the 6003 is great. I got it from 6ave.com in early january for $749. But honestly the 5003 is just about everything the 6003 is, so i wouldnt have any regrets.
P.S.- awesome subs ya got there, my buddy also has dual MFW-15's and they are incredible! You got an excellent finish on yours, kudos.
Great setup, the 82's are great stuff especially with the 64