I had the JRS-X briefly but it wasn't for me. The batteries were very difficult to get to and I direct solder all my packs, plus loading & unloading the batteries from underneath the chasis was a pain.
RDX has been on fire, they have had great performances both at Snowbirds and Reedy along with the XRay T1FK05. If you plan on running asphalt you should take a good look at the Pro 4.