I say hit em hard and fast.
Let's say that those Sherlock figures were two Who's. I believe everyone would have still jumped on them.
BC have those and 1, a second 11 and possibly a second 10 lined up for the first and second quarters I'd guess. That's 5. I'd prefer my schedule !! I'm bias. Rather have new figures than second versions of ones we have.
Whoa, slow down there, young man!
Regarding the second 10, I think it would make sense for them to wait a year or two, to allow anticipation to build. By the time 2015 comes round people will be desperate for a new 10 to be announced (he'll be going for three times the current price on ebay by then).
I think a new 11 is a good idea but only in the next six months. The execution of Ten is such an improvement on 11 that they ought to get a new one out asap.
They should do a Capaldi figure asap because you never know how long he will be around for. He's embarking on a very, very gruelling schedule and his contract is only for one year currently.
If they do a new 11 and Hartnell this year, plus Capaldi and the Sherlock figures that's quite a lot. I would not like BC to overstretch themselves. Three doctors a year is enough I think, plus figures from other licences. Their next doctor after 1 and new 11 should be 9 because they'll make a ton of money on him.
The year after, 2015, they should do a Troughton without a shadow of a doubt, and a new 10. Two reasons for Troughton; first, he's popular but not as popular as Pertwee, so they really want to sell him first before they put a Pertwee out. Second, by that time we should be well into a bunch of new DVD releases of newly found Troughton episodes, giving him a great media profile.
After that they should do a new 4 and then Pertwee, the last of the classic Doctors who I think they can pretty much guarantee selling a thousand of. A new 4 with a different HS wuld sell to people like me who want a 'grinning' head, hopefully on a season 17 outfit. The only other outfit they could sell for 4 would be a Season 18 outfit down the line (serious face, no eyepopping). They should also remember that Tom's not getting any younger. As for the other Doctors, I just can't see them selling out - Tom hasn't sold out yet after six months - and they should only make them when they've diversified into other lines (daleks, other licences) to avoid another Amy situation.
But anyway, the future looks bright, for BC and for us.