I have a Stages bike I use for racing. The lag really stinks with Apple TV. I see recommendations of connecting with Apple TV and the companion app but in reality I have been unsuccessful. Basically there is a big lag that causes surging/falling off. Has anyone successfully connected with the left PM for power and cadence while using the bike as controllable? This is a huge let down if I can’t get this to work properly with Apple TV.
There will always be some lag, but you haven’t said how large a lag you are experiencing, so no one can tell if it’s within normal bounds or not.
Atleast 3-4 seconds.
I have an SB20 and I’ve successfully used Apple TV. I’d replace the batteries in the crank arms first to see if that helps. I use a gaming computer/monitor now because the graphics are so much better. Good luck and I hope you get it figured out.
I use the Stages bike for racing (not with Apple TV). There is definitely some lag responding to changes in power and a learning curve to modulating power correctly in groups. I have no idea how it compares to other trainers though.
My strategy for pairing the left arm is to first pair power/cadence/controllable to the bike for all three, then unpair power from the bike and pair it to the left crank arm. Repeat for cadence. (When using ANT+ I don’t need to do this.) This dance is known as “pairing tetris” on the SB20 Facebook group 
I use it with appletv but the lag for racing sucks bad. It’s fine on iphone or macbook app where u can connect all devices