I haven't been checking the temperature of my return run, but I will check it in the next few days. When I last checked, with no load, it was only a degree or two loss. I have been taking my outlet temperatures right at the outlet pipe (can you see the photo that I tried to post? I have drain valves plumbed so I can shut off circulation and draw hot water just as it leaves the tank), before any circulation to the house; this way any heat drop in the line (by house demand or loss in general) is not a factor. I do not have the thermostatic valve installed.
A comment made by E Yoder earlier got me thinking that maybe CB was counting on the pump driven circulation to the house to contribute in moving the water from the heated side to the outlet side within the tank. I have been running a Taco 009 pump for house circulation, and that is a relatively low volume pump. I have installed a Taco 011 (as seen in my photo) that does shunt outlet water to the return port. This additional tank circulation resulted in a minimal increase in outlet temperature.
I have previously checked the FireStar temperature reading and accepted it as accurate, guess it is time to recheck it.
Your comment regarding a wet fire box with a 185 setpoint and dry at 190 . . . a change I will make after I get my temperature issue resolved. THANK YOU BOTH FOR YOUR INSIGHTS AND COMMENTS.