RCD 310 stereo in pre-facelift '07 Leon - Battery drain

[Chuggerbug]

I'm in the process of upgrading the bog-standard stereo unit in my '07 Seat Leon Cupra (pre-facelift) with a RCD 310 unit. I've got the replacement fascia and just waiting on the stereo to be delivered (brought it for next-to-nothing which is why I didn't go for the more expensive RCD/RNS 510's). My concern is whether or not the CAN gateway is going to need replacing / upgrading as I've heard rumours that by installing a RCD 310 it can cause battery drain on early models of the Leon. Could anyone tell me if this will be an issue with a '07 pre-facelift or is it an unknown until its plugged into a VCDS or the battery goes flat!!