IMO; "experience" is something located at the location is happening, in this case, the train. The consciousness of the subject is right there, not in any other place... now.. that if we cut the link to the brain the consciousness would return to the brain (assuming that consciousness can happen without any propioceptive or senses information) is correct, as the brain (in relation to the senses) is what allows experience to happen.
Well are we dealing again with experience being equal to the word perception? Because I agree that the brain, assuming all all PNS activity were being transmitted "perfectly" to the brain even with the distance the PERCEPTION would probably be that the subject would perceive his or herself on the train, not as a brain in the vat. This is simple to explain; the brain itself doesn't have the "probe" of the body to determine where it is (maybe it does if there are receptors in and around the brain that determine location, but that's a minor consideration to the experiment you're talking about) regardless all perception would determine that you are indeed on the train.
However, ALL that perception IS transmitted to the brain where the perceptions are summated. That's why I actually think the one subject being in two places at once is accurate.
Example: Let's take the BBC Horizon video to an extreme. Let's have the one guy with the screens be labeled (
A) and the guy with the camera labeled (
B). We already see the effects of when the two are standing across from eachother,
A receives the sight stimuli from
B and the brain interprets it as it being his own stimuli. Well let's send
B on a train then.
A will perceive
B as still being himself throughout the train ride, at least visually.
A might as well JUST be the brain in the vat at this point too! But it's still the stimuli of
B's movements being summated in
A's brain. For all intents and purposes he might as well be in both places. It'd be basically a very very very complex periscope/fiberoptic eye.
B is a prosthesis of
A.
A does the perceiving, and
B is just the probe that transmits the stimuli to be perceived.