A couple of things that were said about the flesh Doctor (retention of memory, hoping to see him again) and so on, has led me to conclude that the Doctor we see getting shot is (in fact) the flesh version of him, somehow (icky-sticky gooey-wooey) reconstituted.

In my defense, as soon as Amy said she was pregnant, i announced (to my wife) that River was her daughter.

Oh, and River is going to kill Rory, but I don't know how or why why (yet)

"I believe I can save you some time. That most certainly is the Doctor. And he is most certainly dead."
He also would have turned to goo when shot...

No he would not.

We already have proof that gangers don't turn to Goo when killed.

When GBuzzer gets shot and killed with the improvised Taser his body still stays there. The Doctor examines it and Rory and Amy later cover it with a blanket.

We also see the pile of discarded Gangers who while decomposing have not turned to goo straight away.

Gangers only turn to Goo when the signal to them is blocked/disconected or if the correct setting is used on the Sonic to revert them to their natural state.

As to Canton, surely it's possible he was told to say those lines?

Even if he said them of his own accord how does he know they are true? Is Canton, a former FBI man from the 1960's an expert on cloning/flesh/dopplegangers/androids etc.., how does he know that's the real Doctor?

Actually we know that a ganger being controlled by wi-fi turns to goo when dead (or disconnected), and we know a ganger exposed to the sonic setting turns to goo.

But do we know what happens to when a Ganger who has been "stablized" by time or solar tsunami dies?

I'm pretty sure it is the real doctor. For a start he's 1100, Doctor Goo has no TARDIS, so how's he travelling time?
I think the Flesh thing is a red-herring, it's far to obvious.
Edit: Plus he's clearly had a relationship with river, I'd imagine the real doctor does that, not the goo one.

It doesn't have to be the Ganger Doctor we've already seen.

Whose to say the 1100 year old Doctor didn't pop into a 33rd Century Flesh Factory that morning and have a copy made so he could fake his own death by a lake in 2011.

Two points here, the goo could have replicated the tardis? it was in the mire at one point. Also there is a spare tardis floating around inside the doctors one, that the doctor and (idris) (the tardis) built.

*shakes head* ... the speculation about who may or may not be flesh is going to go past annyoing very soon! ... the Doctor's certainly not going to be fooled again by a flesh avatar ... and the writers aren't going to let anybody get out of a death that easily ...

... the flesh were a useful tool for this series, allowing Amy to be preggers without actually being preggers ... and while I'm happy to incorporate the knowledge of the flesh into my whoniverse knowledge & realise they may be used in the future, there really is no point in speculating over their future use as I'm sure the writers aren't going to let us see it coming and it's beyond boring to suggest that every unexplained death could just be another ganger!

... especially since the stable gangers were from a very specific set of circumstances unlikely to be repeated soon, and as we discovered the stable gangers are just as real as their originals & therefore should be mourned the same way!

The long, hard way like the rest of us. Basically living through it.

But I believe it is the real Doctor, he has "lost" his Tardis and lived rather than travelled through those events.