Also, zx12rider, it is perfectly legal to make your own suppressor. By saying "I'm going the legal route," you didn't narrow any choices down. (Of course, you do need to file a Form 1 with the ATF and pay the tax.)
Anyhoo, I would recommend against Gem-Tech. They haven't been at the top of their game lately, and really haven't been very good at all in the last few years compared to other manufacturers. I would recommend an SWR Spectre or an AAC Prodigy.