Hey, sorry for the really slow reply. I would most certainly go with the 5150-II as well. The E530 is decent, but the 5150-II is a 'real' rig, IMO. The E530 suffers from the same lack of tonal depth that 90% of all rack pre's do. In the realm of rack pre's, it's pretty nice; open that up to all amps, and it's just mediocre. Plus, the M13 is pretty badass. I suspect the G-System is capable of everything the M13 is, but would probably take more work to get there, at least for some of the really crazy effects.
Hope you liked the TITAN clips (& the comparison Rackto clips). I've got a pending trade on the TITAN now for a rackmount MKIV (I've got a thing for rack heads )