Well....That is a good example why shops might not want to use low end regulators in their rental programs - it can give a poor impression of the company's products as a whole as low end rental equipment does not compare well with higher end equipment.
And given that you certified in 1970, it is also a good example of how a low end Scubapro rental regulator in 1970 (probably an early production Mk 3) performed as well as an older top end regulator from another company. Despite your intent, if anything what you stated actually says something very good about Scubapro's reputation for quality and where it came from. And Scubapro was only 5 years old in 1970.
But your statement has absolutely nothing to do with the quality available in Scubapro's high end regulators today or even with the improved quality of their low end rental regulators now (Mk 2+ with an R190, R390 or R295 second stage) compared to 10, 20 or certainly 35 years ago.
Personally, I have used MK 2 R190's to 150 ft and on ice dives (and have also done the same with the older MK3 High performance) and dive with divers on a regular basis who use th Mk 2 R190 to 130 ft in cold water. I also test dove a customer's Mk 2 R190 for a weekend last summer with dives to 130 ft with upper 30/low 40 degree bottomtemps so my experience with one is actually recent.
In my experience, a Mk 2 R190 (the lowest end SP reg in production) peforms entirely adequately within recreational depths and is as good as or better than many regs of greater "quality" sold by other companies, particularly in ice diving conditions as it is very reliable in extremely cold water. To be honest it does not perform nearly as well as say, an Aqualung Legend (a high end Aqualung regulator), but then the Legend also does not perform as well as either the Scubapro Mk 17 X650 or Mk 17 G250 - and Scubapro (incorrectly) considers those both to be "intermediate" regulators compared to their Mk 25 X650 and Mk 25 S600.