No. I think your best bet would be to subscribe to one or the other. Get the Best of either and be happy...
I am going to be closing all my Sirius Account except my one Sirius Radio with a Lifetime Subscription on it. I've already resubscribed to XM and that's what I'm going to be using until the merge everything.
You would in that case have to continue to subscribe to both at the full $12.95 per month. They are continuing to run Sirius and XM as separate companies in terms of the the spectrum and system. Since this more than likely means that the billing and activation can't be merged this is unfortunately the way it is.