A properly set up continuous blending system is actually MUCH more cost effective than PP blending. With a blending system, which you can build for under $300 with an O2 analyzer attached to it... you don't have to O2 clean anything other than the dosing system which is just a needle valve, so NBD there, so no more O2 clean whips. No more dumping of tanks and having to put more compressed air into them to top them off, and no cost of cleaning all of the tanks.
Tom makes a very good point. I 'grew up' doing partial pressure blending, but I did so in a shop that had a truly outstanding fill station set up, plus a 4500 psi booster pump. We could, and did, blend just about everything - enriched air, normoxic and hypoxic trimix, heliox. etc. I loved it. We could, and did, boost 100% O2 to 3000 psi (OK, some will say that was crazy, but we did it, A LOT, without incident. I loved splashing with my 100% deco bottles filled to 3000psi.
But, all good things come to an end, and so did that shop. I moved to a shop where we do continuous blending. My first reaction - what a pitiful set-up. But, once I started using it, started thinking about the possibilities, etc., I realized we can do almost what I did before, with the exception that there is no booster pump, and it is actually easier. I am working on a plan for a control panel to allow us to add trimix capabilities. If volume becomes an issue, we can even add a second Stik station (we don't have the capacity to bank enriched air). I am now a beleiver, in the efficiency and the cost benefit.
Now, dive shops will use this is a way to make more money, because they charge a lot of money for O2 cleaning, and more for nitrox fills.
Frankly, most dive shops have no interest in doing oxygen cleaning. I did it for my old shop for many years, and I do it on a limited basis for my new shop. It is a PITA, it is time-consuming, and the compensation doesn't come close to matching the time investment. I am happy to move away from PP blending, oxygen cleaning, etc.