TTR aka Thunder Tiger. Its a great buggy, but its losing its factory team driver support. I think TTR took a big hit with the EK4, and am wondering if they will put out another buggy to compete with the Mugen/Kyosho.
TTR is suppose to release a ground breaking new buggy some time in the spring. No pics as of yet. Ricard Saxton is heading up the RD and works full time for TTR. It should be one hot buggy when it comes out.
Also, Billy Easton (current IFMAR 2wd world champion) and Jerad Tobo both are STILL run the EB4 S2 Pro with good success.
Bill from National Rc is basically gone from RC, his shop is closed up and does not seem to race anymore. Richard did switch to Kyosho for a while and did very well with it tq'ing the last worlds with a 7.5 but he has now switch back to TTR just like Greg stated.
I would personally hold off on buying a eb-4 s2 and wait for the s3. The s2 is a good buggy but it wears out extremely fast and parts are a pain to get.