sub-pixel rendering

Sub pixel rendering font versions

I am still captured by adapting monitor fonts for sub-pixel rendered environment. Two pics from my font meant to work in small sizes and in negative use white on black ground. To create a version that is similar in weight to the original one has to do a very much lighter character design like the one above in this pic.
But it’s worth while because sub-pixel fonts look so much neater and better!
To see it „at work“ here is my credit page part of my homepage:

Chromebook PIxel: an expensive 239ppi web browsing "netbook"

By comparison, Surface Pro is 207.82 ppi and a MacBook Pro 13" is 227 ppi. My iPhone 4s, by comparison stands tall at 326 ppi, although the next generation of phones (like HTC One) should pass it by.

Should I switch to the metric system when discussing this?