I've been using Mavic Open Pro Ceramics almost exclusively for a number of years now. My experience has been that they give improved braking, wet or dry, when new. In due course - say three or four years use for me, perhaps a couple of months for TG (!) they can become a little "glazed". This reduces their braking efficiency, as you would expect, and I've had some alarming moments in the wet when I've had the levers crammed on to "cable breaking point" as TG described. I set out to see if I could find better pads; I'd always previously used standard pads, not ceramic specific; these seemed to wear OK, except on the fixer (one brake only) which had BBB pads, which wore quite quickly.
Recently, I've tried Fibrax, Kool-Stop and Shimano ceramic specific. The Shimano (Dura-Ace BR-7800 R55C "Ceramic rims only") were poor - no improvement over standard blocks (this is all on an old, quite well glazed, rim) I found a considerable improvement with Kool-Stop - I tried their Ceramic Green (RK-J3 3109-9835 from Dotbike) on the front and the "foul weather" Salmon (RK-J3 31109-9834 also from Dotbike) on the rear. The Kool-Stops are a great deal better; there seems little difference between to ceramic green and the salmon but of course the salmons are on the back, so it's not a direct comparison. The feel is as described in an earlier post - a bit of a pause when little seems to happen followed by a sensation of someone grabbing the rim and sqeezing tighter and tighter until you have to ease off your grip to prevent a lock-up! This delay is much better than my recollection of alloy rims, when you started with a pause when nothing happened and it just carried on that way!
I've also tried Fibrax (number ASH 410C ceramic specific on the front and ASH 410E brown "Xtreme" compound on the rear) on another bike, also with well used Mavic Open Pro Ceramics - as with the Kool-Stops, there doesn't seem much difference between the two colours, albeit again, not directly comparable because the front does much more work than the back. If anything, the Fibrax are even better than the Kool-Stop - just as grippy and perhaps a bit more progressive; but there's not much between them.
My recommendation would be to go for the Ceramic rims with either Fibrax or Kool-Stop ceramic specific pads. I haven't tried the recently advertised Swiss-Stop (? - from memory) stuff yet.
Neither have I tried rubbing over the used rims with fine wet'n'dry to break up the glaze; that was going to be my last resort, but so far, the different pads seem to have cured the problem.