Hi.
I treated myself to the HMEC250 about a year ago, a fab headset and i love it.
The talk through function is very clever, however i really only use it on the ground - during before start checks, during startup etc... We do this off-mic in my operations to avoid distracting the push back crew.
Using talk through in the air is not so good, the mic's pick up a lot of wind/ambient noise and amplify it. Though, i guess it depends on the flight deck. I'm currently on the Q400 and the air conditioning in the flight deck is pretty noisy.
The headset though, pretty good! Lightweight, folds flat, get great battery life off a set of rechargeable AAA's. It's also really comfy, no problems after wearing it all day. Couldn't say the something after wearing the KA-25's, but they were company provided....
Hit a showroom, check them all out as they vary significantly.
Enjoy!