Now this makes much more sense - and I agree that the SCR catalyst would get clogged up quick without a DPF in place - although my point was just a constant dosing rate of urea in order to keep the NO down, although you'd still be letting soot past -
Either way, I would DEFINITELY do the diesel catalyst to cut the stink down - Andrew @ FixmyVW has a nice EGR/DPF delete and includes a catalyst and EGR block off for about $1000 - just add a tune and your axle back exhaust of choice if you so choose -
BMW X5D DPF and SCR cat delete - 3"