OK, I'm a newbie here in the sense that I have rarely posted to this forum. But I'm a Who fan since I was a kid, I grew up in the Colin Baker and then McCoy days, passed the void years reading books and have loved the NuWho, even though sometimes it takes two or more watches to realise that the Moffats stories are quite good! So anyway, I've never watched 'The Deadly Assasin' or other classic episodes which talk about Regeneration.
I always understood that a timelords' life was limited by the regeneration limit (not necessarily a look/appearance limit). i.e. its not unreasonable that: while a timelord is (by default) restricted by 12 regenerations that they are not necessarily restricted to have 13 different faces (i.e. Peter Pratt was a decayed master at the end of his regeneration limit - yet all known previous faces of the master were the same (Delgado) - and this is a trend continued in Anthony Ainsleys days). Using the master again its clear that the 12 regeneration limit can be surpassed, but if left unaltered the default norm for a timelord is 12 regenerations only.
I agree - Tennant did use up a full regeneration, its just he didn't use all of it on himself, just the healing part. So with that in mind, putting regenerations at the heart rather than incarnations, doesn't that mean the doctor has used his regenerations:
01 - Hartnell to Troughton
02 - Troughton to Pertwee
03 - Pertwee to Baker
04 - Baker to Davison
05 - Davison to Baker
06 - Baker to McCoy
07 - McCoy to McGann
08 - McGann to Hurt
09 - Hurt to Eccleston
10 - Eccleston to Tennant
11 - Tennant to Tennant
12 - Tennant to Smith
Again - this is only my own opinion. If the above is how Moffat wants to write the life of the Doctor, then does the "fall of the eleventh" refer to Tenant or Smith? Was it Smith or Tennants TARDIS at Trenzalore? Does this tie in somehow to the exploding TARDIS which I don't has yet been completely explained yet seems to be the reason for (amys') cracks and indeed smiths complete story arc.
Also - on a completely separate note, if they do decide to introduce the Valeyard Character, wouldn't he have happened somwehere between Tennant to Smith.
Finally - Melody didn't give Smith any new regnerations - she just used all her remaining ones up.