So I got a Pantac triple MP5 pouch (CB) off ebay. I went with this one because I prefer velcro to snaps, and they had it in CB.
$30. Shipping took about 2 weeks. No additional bullshit sting charges.
(
http://cgi.ebay.ca/ws/eBayISAPI.dll?...m=170321686847)
Quality appears good, but time will tell. One pouch seems sightly (~3-5cm) shallower than the other two.
MP9 mags fit perfectly. The flaps secure them very well, and with the flaps folded back into the pouches, the mags fit fairly snug. I trust it enough to carry my expensive mags unsecured, even while low crawling.
With the mags in nozzles down, the pouches come up to about halfway between the "25" and "30" markings on the mags, or about 2/3 coverage. If I turn it upside-down and gently shake it, the mags fall out, but they should otherwise stay put without the top flaps secured.
So as long as the stitching doesn't fall apart, this option works for me.