I'm not really considering them for carry, but I've been eyeballing some +5 magazine extensions for Glock mags for a while (19 and 17 mags), and I know the "school solution" is TTI's but I'm not a fan of their retention system. The Shield Arms ones seem to use a similar retention system as TTI, but the Warne extensions are different.
I know the Warne's were made with USPSA mag restrictions in mind. I'm not sure about the Shield Arms. I'm not currently shooting matches, but I'm thinking about starting back into it if ammo and component prices continue to come down, so I'd like to be able to use them there.
Any input would be appreciated.