I own both. I bought my Kestrel the 1st day they were available and I liked it. I liked it even better when I devised the clinch bridge.
But now it collects dust.
I hunted all last season in my prototype Recon and had lots of 11 hour hangs. IME, I don't care what type of stand a guy uses, after about 8 or 9 hours they all become uncomfortable. Even a Lazyboy recliner gets uncomfortable after several hours.
I think size really matters with any sling or saddle. I'm still on the fence about which Recon size is best for me. The small works a little better for me when talking about a bungee belt and different ways to configure the attachment for the bungee. The medium takes a little more creativity for attaching the bungee belt, but it's quite doable. The medium is more comfortable for me while hanging. My buddy is about my size, 5'7" 180lbs, and he has the same opinion as me about the sizing.
It seems like I can't quite separate the 2 panels of the small size as much as I would like.
It takes a minute or so to adjust the webbing bridge while hanging. It's pretty easy on a platform but on a ROS you would need to employ your lineman belt. Having the webbing bridge being adjustable, (IMO) is more for dialing in your bridge length for your comfort level. It's not really something that I adjust on a daily basis.