I previously used a WR Hercules Super BEC
http://www.western-robotics.com/hercules-super-BEC_hp.html. The older version has 5.2V/6V/8.4/9.0V. The voltage options of the newer version may be better for voltages used with helicopters, 5.2V/6V/7.4V/8.2V.
The WR Hercules Super BEC seems more robust than the BEC Pro. The WR is rated for up to 14S, where the BEC Pro has had reported issues when on 12S.
However, I had issues with the Spektrum telemetry signal when using the WR. This may be due to the fact that the WR does not use a ferrite ring, but many will point out that a ferrite ring is not needed when running 2.4 GHz signals. Still, the WR output wires are too stiff to easily add a ferrite ring.
I was also concerned that the WR was only rated to 10A cont/15A max, and the BEC Pro is rated to 20A peak. On 6S, the BEC pro is rated to 13A max continuous.