Okay, I've been looking to get one because I like the design and I think its one of the best set-ups out there to take advantage of the lipo weight savings. However before I do, I have one problem Team Magic's history.
So far their distribution has been shaky and many retailers are staying away or have dropped TM altogether. However, I have recently dealt with Wolf Hobbies and they're a good outfit so I am over that issue.
The next one is my experience with TM on the G4. TM came out with lots of upgrades and updates to the G4 at extremely high costs only to now be found on the G4JS for less than half what the upgrades cost alone.

This just makes all previous model G4s worthless to the point that you can't even give one away.

This is the same fear I have about the E4. Someone here says that the E4 FS/RS is equivalent to that of any XRay or Corally but when compared with the JS version, it seems that the JS is more updated with a more thorough design.(above chassis battery access vs. dropout batt tray) So it seems like its starting all over again. Therefore, if I were to replace my current XRay with a TM car it would be the JS only to minimize myself from being screwed with another model offering so much more for so much less in the next 6 months.
Now the final question, what else would I need to get with the JS to get it running aside from electrics? Does it come with all the necessary parts to tune for toe-in, caster, anti-dive & anti-squat or do I need to purchase additional hubs or suspension blocks?