I like the TRPs. Partly for looks, partly because the "Inplace Adjust" feature makes them very easy to adjust. Other than that is seems to be an apples to apples comparison that you could probably flip a coin to choose.
2013 Kona Jake, 2008 Kona Major Jake, 2013 Kona Jake the Snake, 1999 Kona Muni Mula, 2012 Ridley Excalibur, 2008 Surly Long Haul Trucker
I haven't seen a lot of reviews of the FSA brakes. I have seen a lot of positive feedback on the TRP's. The main negative I've heard was that toe-in was problematic, though I'm not sure that wasn't an older incarnation of these brakes.
I think you should get the FSA's and post some feedback.
The EuroX's work great for me. The only knock is how far they stick out on the back. When I got tired at the end of a race, and my remounts became less graceful ( sloppy) , my ankle and the right arm sometimes tried to occupy the same space.
Not so much now, but it took a little blood before I learned.
I went ahead and ordered the EuroX (got a good price on flea bay). As far as the SL-Ks go, the guy I ride with all the time has him on his bike, he says that they work great. I'v never actually rode them as his bike is a few sizes too large for me, but just tooling around with them they feel like they respond pretty well (compared to my Avid Shorty 6's anyways). I'll let you guys know how I think they compare to the EuroX's once I get them.