Some divers use just finger tight. It's a smidge unnecessary. I go finger tight and a little bit more. It's really hard to accurately get torque readings on these things, but they're 45+- 2 inch lbs for the heat exchanger, and 40+-2 inch lbs for the hose. A "finger tight snug" is all they really need. Just don't crank em way down. I keep mine just past finger tight because I have to move hoses around all the time. Adding long hoses for cave, adding angle adapters for sidemount, etc. They won't come off with just your hands, but with a small wrench on them it's little more than a tap and they'll come off.
Like what you said, it's almost the same torque as going into the first stage. Little tighter according to the manuals. You can double check if you have a torque wrench. Just don't over tighten it, you'll bust something. IF you do use a torque wrench, it is IMPERATIVE you hold the heat exchanger nut on the 2nd stage to make sure it doesn't crack the housing. If you do it by hand, then it's not quite as important, but if you're actually cranking it to spec you have to hold that nut
I'm assuming finger tight and a little more, like going to the first stage, but want to be sure so I don't embarrass myself at the lake this weekend - or hurt my new reg.
