Yeah, that'd be my main concern, too. I think the main plus to doing it from scratch would be all the real estate it'd free up. Although the thing I got hung up on myself is mic placement, if used in tandem with a voice amp system. My gut instinct would be to place the mics for the ambient sound amp system in the aerators of the helmet, so you wouldn't have to mod the helmet itself externally, and plus you really just want the sound in front of you amplified. But the main issue I see with that is feedback from the voice amp, which I'd like to have mounted under my chest plate. I can see where the mics might pick up your own voice, and give feedback. But that might not be an issue, based on the placement of everything. Also, at least for my helmet, I might be running out of space here. I'd like an Aker voice amp with the Memorex wireless transmitter, a circuit for audio amplification, as well as the much needed fan, and foam/harness/whatever system I decide on for securing the fit of the helmet. I'll have to do some serious planning, that's for sure. But as soon as I get closer to having parts in hand, I'll post a WIP thread, and you can be sure I'll be posting trial and error for the audio amp circuit.