Looking at the website, I seems the expander do not have any functionality to eliminate RF noise due to long leads.

Anybody know which one will do:
-provides full power to servos and clean power to receivers
-optically isolated
-Allow use of two batteries. Do not require separate battery for receiver.
[link=http://smservices.net/acatalog/Large_Model_Units.html]SM Services[/link] have one that's optically isolated, but requires a separate receiver battery. The also have an optical isolation unit only.

I guess only the powerbox does it all.. (?)