For me the best solution would be for the Doctor to state that they were originally limited to 12 regens but Rassilon removed this restriction during the time war.
Now, if that was the throwaway line in SJA I'd be impressed.
For once, this isn't something that bothers me.
Admittedly, I've only watched the SJA eps with 10 in them, and will prob only watch the eps with 11, so I can appreciate people not liking it being in the spin off show, but the way I see it they'd have to do a massive drawn out thing in Nu Who for 11 to explain everything to Amy & Rory (and therefore the Nu viewer) - but then again, Moffat could just as easily pull a "wibbly wobbly timey wimey" on us too.
I won't lose sleep over it.
