first it is an ex-10 eurus, the ex-10 helios is the previous radio. and the ex-1 is the ur.

the old 2.4 works just fine. you do have to turn on the radio before the rx. most of the time i have had it work even when turned on in reverse. but once in a while i have had it not bind when the rx is on first.

there is an update to the original 2.4 901module. just pull the module and look at the circuit board near the holes where it mates with the radio. if you see any color other then green, then it has the update, if not, you may want to send it in to KO and have the update performed.

the new 2.4 902module is a newer module and is much faster. it still have the quirk that you have to turn on the rx before the transmitter. but to me that is a safety thing more then anything else.