I'm using a pair of Tac 6's, they work great, albeit i havent used them in a hot environment yet. the batteries last a long time (ive worn mine for around 14 hours now without a battery change), and they work really well for blocking out sound when its too loud, and allowing more sound when its too quiet. they also fit really nice under my helmet.
ive worn mine on the range, and a live fire ex involving helos with door guns, patrolling, and lots of shooting. in the helos and with the guns going, it was a dull thumping noise i felt more than i heard. on the patrol, it allowed lots of sound in and easily allowed me to hear everything going on. this was at a temp of around -5 to -10, so not exactly afghani summer tempatures.