Haven't really had any problems with the BRG process, at least nothing new since we had to email (which is a pain).
Had a great BRG in Phuket (mistake in my favour) and got another one for Siem Reap yesterday to $113/night - competing site was Booking.com for the first time. Yet another for GH Bangkok, GH Doha, not sure what else in the past month or so.
If you do a lot of BRGs and generally in the same markets, you learn which sites are accepted, which hotels tend to have BRGs available and what a good rate is so you accept it though Hyatt.com.