I bought the Rally XC 200 the week before Unbound Gravel when there were reports of lots of mud on the course due to all the rain. Normally I run Favero’s on my gravel bike.
I put them on my MTB bike first as it has a Quarq and then put that on my Saris Hammer H1 trainer to do baseline test. Power over 2 rides was consistent and tracked with the Quaq and Hammer. I had tried out a pair of Vector 3’s 2? years ago and they were consistently inconsistent leading me to get rid of them.
The Rally’s worked fine for the entire Unbound race. I made sure to recalibrate them just before the start of the race as per the instructions and wisdom of the internet 
I’m not a fan of the SPD cleat interface as I seem to be one of the few that has problems with their shoes (New Garmin Rally XC Pedals, Loose Cleat/Pedal Interface - #10 by Salvo) and it’s not something I want to deal with so I will be selling them.