Funny how some people are having issues and others have not. Been running Spektrum since 2002 when I saw a little girl take a 1/8 nitro buggy to the face from someone else being on the guys channel ( days of clothes pins and crystals).

Since that day, I have never had issues with any spectrum product. Call me lucky I guess. That's 5 different transmitters, and probably 20 or so receivers. I still have my original DX2 that I use for motor break in. It runs a HiTec 645 servo and 3000 Rx on 4.8V rechargeable AA batteries for about 45 minutes without issues. For racing, I have NiCd's, NiMh, LiFe, and LiPo packs. The non lithium batteries have dropped down to around 5 volts in a long main without issues until the servos just quit working and the LiFe/LiPo's run just fine for a minimum of an hour. I just recharge them at about 6.2-6.5 volts just to keep them peaked out.

On the transmitter side, I was running regular, Duracel and Energizer AA's. Rechargable ones too. Warning beeper was going off during the whole 30 minute main and no issues. I went to the NiZn just to try them and see what the WOW factor was. Fully charged 2500mAh NiZn will last for 30 hours and still not drop below 6.5V. I figure that's pretty dam good since the regular AA's will maybe hit 6-6.3V brand new out of the package and be down to 5.5 in one race day.

I think it has to do with a lot of the newer "features" that the radios are coming with, the high current and loads from these super fast/strong servos and BEC's from the ESC trying to compensate for that draw causing issues.
And from users that may not have their equipment set up correctly....