Diesel298:
well short answer is yes. better materals meching, and performance.
but there have been no astonishing breakthrus im aware of, just improvements on existing designs
I agree with you partially on this. There has been no great leap forward in performance, and their have been imporvements in production efficiency, but quality has not improved.
Reg performance has not improved significantly in the last 20 years. For example an early 80's vintage Scubapro Mk 10 Balanced Adjustable still breathes as well as any reg you could buy today and is more than enough for any recreational or technical diving task.
There have been minor imprvements but they are evolutionary rather than revolutionary and not all of them are relevant. To use SP regs as an example again, the Mk 25 uses an overbalanced piston design that ensures basically zero change in IP as tank pressure falls from 3300 to 300 psi whereas the Mk 10 had a 4-5 psi difference across this same range. But in practice, this makes no difference to the diver as performance was still excellent despite the slight change in IP so the improvement is more theoretical than practical.
The MK 25 also has a flow rate of 300 SCFM which is about twice as much as any diver ever needs under any circumtances. So a Mk 10 with half the Mk 25's flow rate still offerred all the performance ever needed, so the improvement is nice but not all that important as it really did nothing to meet an unmet need.
The MK 25 also uses a thermal insulation system that requires no silicone but it is less than 100% relaible in very cold water (less than 40 degrees). The Mk 10's silicone filled environmental chamber needed more maintenence but when properly serviced it was 100% effective. So whether TIS was an improvement or not is debateable, (although it does do a superb job in the Mk 2 and Mk 16.)
The Mk 25 uses a replaceable bushing system that allows tighter tolerance that reduce HP o-ring crimp and allows higher service pressures (up to 4350 psi/300 bar) and these tolerance are restored at every servcie when the bushings are replaced so the first stage body in theory can last virtually forever. On the other hand the Mk 10 will theoretically wear in this area dn eventually develop problems with HP o-ring pinch, but I have only found this occurring once in a Mk 10 and there are literally tens of thousands of them still in service, some for well over a quarter century. So wear in this area is not a real big concern. And while not a good idea, a Mk 10 could go 4-5 years between services with adequate care. This is a bad idea with a Mk 25 as the plastic bushings should be replaced more frequently than that. Finally, the Mk 25's 300 bar service pressure is nice, but I have yet to actually meet anyone who uses 300 bar tanks. Despite predictions otherwise, the trend has not been in the ever higher pressure direction with most people instead buying tanks in the same old 2400 to 3500 psi range.
The same trend in "improvement" applies across regulator brands. There have been detail improvements but nothing that really makes performance noticeably better. In the early eighties, the scuba first stage regulator pretty much reached a design peak in terms of performance and has plateaued since.
I would argue on the other hand that second stages designs have in some respects sufferred. The dive industry asa whole screwed envery diver around when they went with plastic second stages. They created dry mouth and cold water problems that were unheard of in metal cased second stages. They also created the potential to crack or break a second stage. In contrast you could drop a tank on metal cased second stage and not phase it. If you did somehow manage to dent it, you could hammer it back out and go diving. They also still look good after 20 years with a nice satin chrome look while a plastic second stage looks 20 years old after about 20 dives.
Plastic was great for manufacturers in terms of low production cost as they can mold a plastic second stage case and sell it at a profit at $5.00. And the marketing folks convinced divers that the more complex shapes possible would markedly improve breathing performance. The problem is tha 20 years later it has not happend yet and the cost savings from plastic have also never been passed to the diver either so they lost both ways.
