I've never had an issue (or even heard of an issue) of this kind on any of the following keyboards that i've owned: any unicomp, any ibm, any non-filco alps, any scorpius m10, any cherry, any topre, any DSI... wait a minute - basically any mechanical board i've owned so far except for filco.
psssst, but dont tell the cavalry (ripster + itlnstln) that...
TBH, the Realforce 87U I got from you last month does already have a noticeable shiny spot on the spacebar. And it's not something that appeared last week, it was already visible when I received it.
I want to be clear, I am super happy with this keyboard and believe I got a great deal from you, plus the transaction has been perfect. I'm just saying that this keyboard (which is maybe 6 months old?) and has probably the best keycaps available today is already getting shiny, so I don't believe this is a problem only related to Filco keys.
The board I was using before the Topre, a Cherry G80-1800 I bought new (with black double shot keycaps), started to show shiny spots after maybe a couple of months of daily usage.
The one I used before it, a Cherry G80-5000 which I received almost new, (white double shot keycaps), started to show shiny spots in a couple of months too.
The same happened with another Cherry, a G80-11900 with black double shot keycaps that I bought new from eBay.
The Dell AT102W, with black keys, which I bought 2nd hand on eBay, I've already received with the letters partially worn off.
The only boards that survived in my hands a long time without exhibiting signs of keycap wear are the IBM Model M.
I never owned a Filco so I cannot say for sure, probably it's true that the keys start to wear more quickly than other keyboards, but maybe, I repeat, MAYBE, this issue is being exaggerated a bit.