I set up my 3 flashpoint 320m I ordered and finally got to play with for the 1st time. I experimented with my impact 45" umbrellas as a shoot through and bouncing with the black backing installed. I had several issues with the strobes not firing with the sensor. I went to use the pc sync and soon found out the 60d doesn't have one. I had 2 yongnuo Rf602 so I mounted one on the hotshoe and the other on one light to pc sync and that would fire my main and fill light but no background light. So my question is should I buy 4 yongnuo Rf603ii transmitters since I read they sync to 1/320 where the 602 is 1/250 or go another route?