Interesting. Of course any manufacturer making a platter is likely to be trying to get the best solution - and it costs what it costs. So if ETP is a bit better than the Al/CU one and the ETP is a reasonable cost for what it is, the fact that the additional cost of upgrading from one good platter (Al/Cu) to another good platter (ETP) is "not worth it" is not the fault of the new better platter. Starting from scratch, without the original investment in the first upgrade, the ETP is presumably fair value. At least, whether or not it is fair value has everything to do with how well it performs, and the price compared with production and distribution cost, and nothing to do with what another upgrade platter does or costs.
Regarding the "not much difference" I think this may be due to some confusion about what a platter does. I have corresponded privately with Cagey about this (he initially found no difference, or negligible difference between funk 1 and strata), treating him to a brief history of Pink Triangle product development, and the "science" or theories at least behind the evolution from acrylic to achromat to strata. A lot of the issue is that the "thing" (platter and mat if there is one) is really record support and termination. They are an integrated function. Pink Triangle pioneered this by having a platter which did both jobs, instead of termination being the mat, and support being the platter. But what works goes beyond just getting the platter/mat right - and depends on how the turntable itself deals with waste energy from the stylus.
So, if your mat is the termination and doing a good job, all that is left for the platter mechanically is to support the mat and record - and 2 quite different platters might do that equally well, or similarly well. With a different mat there may be more difference in the platters(or no mat - I had a feeling ETP could be - maybe should be - used naked)
I gather the bit of Pink Triangle history has helped Cagey get things working well in his system after a hesitant start.
