andy,

My concern would be the handgun catching you in the nuts when you sit down...

I haven't tried the "Thunderwear", but I've tried IWB holsters and a lot of other ways of carrying a handgun and only found one that works really well for me.

Kramer Leather makes the Confidant Shirt, and it's the best way I know to carry concealed. If you're going to carry a heavy gun, order it a size smaller; otherwise order it to fit.

I wear mine under a light western shirt or a loose fitting t-shirt and I've never had anyone spot it. Very comfortable.

Here's a link

Daryl