I tested GOES-13 (same frequency range as GOES-16) with outernet. It does work fine if you have a big enough dish (like a do), but its easy to do a Linear feed or Single CP feed (like a helix) that I think it doesn’t worth it.
Also the GRB has two independent channels, although its good to receive both, you dont need to necessarily. They transmit different data but they’re complete independent.
So far I would not recommend trying an SDR System with GRB (at least one that you will do the demod in your PC), since the GRB Rate is very high (about 15Mbps per channel). Since they use DVB-S2, its best to get a DVB-S2 commercial receiver that can support any type of stream and use it. It costs about the same price of an SDR and might even have two channels.
I’m in the process to build a GRB station to make the tests and see whats the minimum usable system (NOAA recommends 4.5m dish for GRB!) and see which hardware can be used. There are some (few) other people that is build as well. You’re welcome to join to test it
Sadly usa-satcom (on twitter) tried with a 1.8m dish, and even with a perfect system and weather, it was not enough to have demodulated data (although it was pretty close, about 1 or 2 dB off on SNR)
EDIT: Just saw you’re planning to use with the TBS, thats the way to go. Although usa-satcom did a test and it can’t even find the signal with a TBS, then dr.mpeg on twitter did run with the same IQ with a higher grade hardware (Ayecka) and got almost locked.