As far as I know, the velcro-covered pocket interior and velcro-covered pouch exterior system (they call it the Accessory Platform) is a DBT thing. I haven't owned an EPC in a while, but if I remember correctly, the entire pocket is not covered in velcro, so it's not really meant for those pouches. It was designed as a pocket for a pistol or other misc stuff.
And a word to the wise: Unless you've tried it, I wouldn't go and buy a bunch of SR-25 pouches for SCAR-H mags, only to find out they don't fit comfortably. I'm sure they'd sit well in the pouch, but maybe not optimally. There's a reason multiple companies make both SCAR-H/M14/G3 magazine pouches and SR-25 pouches.