Tekin can clarify, but it seems like the RS only want to see 6v. I have a regulator, but opted not to use it just to save weight. I'm going to put it in now, but I still need to get another.

And now that I think about it, there have been a few people who have mysteriously failing RS's. I can think of at least two in the past weekend. I can't say for sure, but most people are running 2s rx packs. I have been running a booster all carpet season and only ran a RX pack strait to the RS for the first time this last weekend. I guess I got lucky.