I owned both, the 6E used AA batteries until you upgrade. Very similar otherwise, the 6E is "economy".
Spektrum had to be dropped because the RX and protocol is not as compatible as other units. I purchased 4 different Spektrum TRX and close to 20 different RX and verifiably concluded that the RX configuration was to blame, specifically interference from carbon fiber on the frames. Many walk of shame because of Spektrum, luckily no one was hurt, but I do consider Spektrum data protocols o be a liability.
Other hits against Spektrum, because it is quite important:
- They are well known for stealing clients from independent hobby shops (several reports via Horizon Hobby)
- No repair manuals! This is VERY VERY BAD!
- Repair only by their service center (part of how they steal clients from small shops)
- The firmware has bugs. For example - I totally reverse engineered and hacked a 6e only to find out that travel of the potentiometers beyond certain values would reset the position to 0/middle.
- Telemetry is optional and expensive
The technology used by Spektrum is plane-centric. Once I switched to FRSky, a drone aware engineering company, I was shocked when everything worked and my performance on data (TRX/RX) more than tripled.
If you are looking for an upgrade do consider FrSky/Taranis. I met that team and spent some time with them - they are in it to win it. Spektrum is part of a large conglomerate that is tied up with a lot of dirty stuff. In fact, they are owned by Horizon Hobby.
Personally, I have always considered Futaba to be the best choice for heli, I may be wrong as I am more invested in FPV than anything right now.