EC-C IV vs. EC-S focusing screens for MF with lenses 2.8 & faster

I would like to hear some user's opinions on the two when it comes manual focusing 2.8 and faster lenses (as the title indicates). I want opinions from those who have used both and/or used one or the other.

Any insight on these screens would be immensely appreciated.

so let me preface that i'm not a huge manual focus guy, but i found the XX-S screens too dark even for 2.8 zoom lenses. it was great for primes though. fwiw, i sold my XX-S screen to someone who absolutely loved his. i suggest you just buy it and test it out, it's something you really need to experience for yourself.

I didn't like the EC-S on my 1D III, but I didn't know if perhaps it was an advancement from the 1Ds II OEM screen.

Wait, did the 1D III take the EC-IV or was it only the 1Ds III? I think that might answer my own question, but I want the debate to go on.

I second that. I got the S screen for 5D2 tried it once and sold it the next day. It's just dark even on 2.8 and 1.2 lens. I'd say a good 2 stops darker than the default.

Right now am looking out for the Ec-N for my 1Ds3 which I heard is supposed to be a good half stop brighter than Ec-CIV.