When I play MVS on my cab, I just usa 1-slot mobo ($65-75).
I equate the CMVS to the AES console - equally.
So it comes down to which you prefer. The CMVS console is slightly more expensive than the AES console, the MVS carts are almost always cheaper than AES, particularly on the very very good stuff and the "new" stuff (games still being released, etc).
I'm not a huge fan of shockboxes. I had 40+ of them, bought all new, and 6 of them developed cracks from very very delicate usage
The artwork from southtown however, was legit.
I now use the neo mini-box, about $4 per, after shipping is included. An exact fit for the carts, so a much smaller footprint. I've had mine about 10 months and zero signs of wear / swelling / or other cosmetic concerns. They are coated and firm, spine sticker sets run about $1 per title.
Here is my current setup:
