I stealthed DPAs w/ the MMA6000 and an R-1 many times. I've never seen the preamp Church has, but I'd imagine its not as large as the MMA6000.
I'd opt for the versatility of his preamp instead of the battery box. That's just me though. I had the 4060's, and taped a lot of metal, and I never had to use the gain on the MMA6000 at all. However, the 4060s are a little more sensitive than 4061s, so keep that in mind when interpreting my statement.