IDA. You are still implying that the MK2 works just as good, as the MK2 EVO & mocking, I wasn't born yesterday, don't turn it around. Well, it still doesn't & those times passed 60 yr ago, like education. They are NOT the same & I've heard it all before. That knob is better than the old one & increases U/W VIS, 3x better than the metal one. It isn't even my point but to expand on, what you take light & mock, the yoke can be grabbed, with nails & fingers, less slip & uses different material. You would know, that the metal knob alone freezes then & can't be re-incorporated today. Actually, the Navy prohibits 1/2 of the equipment but I'm not telling you why.
The old T-knob is vulnerable to entanglements, meaning, the new EVO will have saved someone's life yesterday, today, tomorrow or eventually. I've seen it, at 100 ft, lines getting stuck on the T-knob & divers struggling to get out of that junk reg, that you say is the same, instead of smoothly going over it altogether. There are bad advices & practices, you don't want to promote, to students
That spring has double the coating & different material as well, compared to NONE (Z-E-R-O). The EVO will last 40 min, your entire dive, instead of freezing in 10 min & can supply gas for 2 divers to meet current regulations.
Because hearsay isn't enough to dive with us. You would still need certified & documented maintenance services. Obviously, you aren't an instructor & don't have students, there are liability issues & diver oaths. What kind of equipment safety protocols are you following & teaching then, Jesus? No certified diver is supposed to teach self-maintenance for regs & everyone knows it. No sensible tech diver will dive with a buddy using a T-knob, after, what I've seen, in the pitch black.
There are big differences
BAD ADVICE, DO NOT BUY AN OLD ONE & JUST DIVE WITH IT, AS BEING THE SAME - No Thank You
Retired Navy
. And they can be ornery 
