I have a CA G36C, and was originally planning on getting the whole G36 line to to try all sizes of rifles to see which would fit me best. However, about the time that I was considering getting my second rifle I was also getting interested in using standard mags. I have some cheap tac gear( also still experimenting with that) and the pouches that hold 3 M16 style mags I could not even fit 2 G36 mags into. Now granted it is cheap gear but there is a divider in the front that holds the 3rd Mag, so other pouches might not have that problem. But I bet you will only still get in only 2.
Maybe Pouches for AK's might be better and I thoujght of getting some, but switched my second gun choice instead and went with a M15A4. I found Standard mags for the G36 hard to find except the really small ones(20 rnd). Plus having metal mags seemed appealing.
I have heard that militaries that use the Real steel G36 have belt clips that the mags just snap onto using the hubs that connect the mags together, but have never seen or heard where to get them. That would help alot.
In short, If you like High-caps then there is no downside to the G36's mags. 470 rnd Hi-Caps with 2 locked together, your going out on the field with almost 1000 rnds at the ready!
But if you wanna go standards then the downsides start to grow.
Just what I've discovered in my admittedly limited expierence.
Be Well,
Phyrst