Higher air delivery of air not higher work to breath. as far as your last statement about EU testing i have no clue what that is about. I will guess that the 60 ft bench mark is a testing thing only. the article i read took all the regs deeper till they started to breath harder and did not find where the SP MK25 breathed any different than on land. I think they stopped at 220 feet the rest all developed to some noticable degree a reduced air flow or more effort to breath before that. That is what made my choice what is was. I self concluded by the info thta if i had to share air at one hundred feet I would not want to get it from someone that used a reg that started to pull harder at 125 ft. panic at 100 is double te air demand for 2 people so its like supplying 4 divers breathing normal. Of course this is not very techincal but say the reg was years old and never rebuilt and was unknowingly only working to half capacity could I still bring someone up sharing air. Scientific or not that made my decision to purchase. I ve been using them since 2003 and i probably have 6 of them. they all work flawlessly.
We have in our club a reg maint guy and that is where i got told that piston regs all in all deliver higher flow rates than diaphram regs. and that I would be hard pressed to demand over load a piston reg.
