I love mine, but few points to get the most out of it. It's a lot of stainless to bring to temp so be sure to up your strike temp or better yet, preheat with 170 F water.
I've mashed as little as 15 pounds of grain at 1.25 qts and your temp lost is greater at these lower masses. At grain bills similar to OP, my MT thermometer stays pegged within a degree for 1 hour on my unit. But checking around with a thermpen, the edges lose about 4 degrees while the center about 1. I'd estimate the average temp lost at 2 to 3 degrees.
My efficiencies are 85 to 88% fly sparged, with a crush that is probably a little too fine, from a particles in wort perspective, not stuck lauter. I'm at .034 or .035 on a barley crusher. With just barley malt, I think it would be difficult to get stuck
I've replaced the stock thermometer with a dial thermometer that I can calibrate. I had to enlarge the hole in the MT in order to do this.
Overall I'm sold, mostly because I like shiney though it functions well enough.
My first winter use is around the corner. I expect temperature losses to be greater. If they are not to my liking, it's insulated well enough that I think I can get away with a manual HERMS, recirculating for a few minutes mid way through the mash