I bought 2 (was given an additional mag as well) of these magazines back in April.
I experienced many issues, and the magazines were generally unreliable. The issues went away with a different follower and spring.
I ran into Dave from MSAR at the NRA show and he gave me 4 more: 3 translucent "amber" and 1 opaque OD green.
A quick test of the follower shows that the amber magazines, marked 04/09, had the same issues that the earlier 03/09 production mags did. Range tests confirmed this as well.
The OD green magazine, however, marked 05/09, worked fine, with the follower and spring it was supplied with as well as the follower and spring from the 03/09 and 04/09 mags. Apparently a change has been made to the mag body...or perhaps the opaque polymer has more inherent lubricity.
It did not, however, drop free from any of the receivers I tested it in (Colt, Sun Devil, POF, Stag, RRA). None of the mags performed very well when placed in pairs in standard M4 magazine pouches - either they wouldn't fit, or they both wanted to come out at the same time, or they didn't want to come out at all. I think this magazine would benefit from a pouch with separate compartments for 2 magazines.
From left to right - 05/09, 04/09, 03/09