Quick update: I think I've settled on 50psi. Yes it's a little bit slower but wow is the ride really comfortable. I fully realize and embrace that my time on the FX S6 is not meant to compete, speedwise, with the TCR and S3. It's serves a totally different purpose. I went as low as 45 and as high as 60 on my tubeless 35c Panaracer GravelKing SK TLCs. 50 is the happy medium between plush ride without sacrificing too much speed. For testing purposes I rode my usual 14 mile city route, which includes many stoplights. I was only 3mph slower overall than my road bikes. And because of waiting for stoplights, even though the overall mph was lower, the time to complete the route wasn't that far off. But instead of feeling every pothole and significant bump...I just rode right through them like it wasn't a thing.