To put things in perpsective, these are the combinations we can safely assume they work well or have been tested:

Spektrum DX6 and BR6000 (most of us have this)
Spektrum DX5e and AR500 (provided the esc and/or rc-switch has its own failsafes)
Spektrum DX6i and AR500
Spektrum DX7 and BR6000 (Also been done before)
Spektrum DX7 and AR500

So basically, if you own a DSM2 TX go for the AR500 RX if you need no more than 5 channels. For DSM use the BR6000.