I totaled both RMS and XV Level II setups
I wanted for my application:

RMS:
ARC4000L LevelPro compressor system w/ aluminum tank $2,070.00
ABAR20700 Mopar 68-70 B Body & 70-74 E Body rear AirBar w/ dual adjustable Shockwave $2,265.00
AIRBAR Air Ride Shockwave double adjustable $798.00
16160 Tubular K-Member Conversion B and E-Body Power Steering $3,595.00
16160 complete 1.125" sway bar $249.00
WIL-140-7018 Superlite 6 Piston 13" Big Brake Front Kit $1,250.00
total= $10,227.00

XV Level II:
20-1201 XV E-Body Level II Suspension - Front $7,495.00
20-1221 XV E-Body Level II Suspension - Rear $3,395.00
25-1201 XV E-Body Level II Brakes - Front $2,895.00
total= $13,785.00

when I add up the parts total of the XV Level II it is roughly $3,558.00 more for my application

but what is not included is the amount for the extra welding of the XV Level II
I would guess it would cost maybe $1000 for the proper welding procedure?
if so it would only cost roughly $5000.00 more to have the XV Level II installed for my application

bottom line is cost
if there is any way to lower that extra $5000 difference to be more cost effective with the RMS setup,
then I would choose the XV Level II in a heartbeat