Be forewarned, if you connect the GoPro 2 directly to the BMD HDMI-to-SDI mini-converter, and you have it set to 1080 in the GoPro, the mini-converter will set it to 1080p, not 1080i. Not sure if the TriCaster supports 1080p or not.
I believe 720p works just fine.
If you need 1080i out of the GoPro, you need to use a Gefen HDMI Detective in-between the GoPro and the mini-converter. Obviously, after you’ve set up the HDMI Detective (stored the EDID from the TriCaster).