Only theory, but....

I do not believe that the pressure in the receiving vessel is reduced to any substantial degree.

You are starting with an empty receiving carboy at atmospheric pressure (i.e., filled 100% with air). You pump a little bit of the air out, and the wine in the filled carboy starts moving into the receiving carboy. Consider how much (or how little) pressure differential there must be between the carboys to make the wine move. The minimum would be something like 6" water column, or 0.2 psi (which is a reduction of approximately 1.5% of an atmosphere). That is the minimum, but say it is, I dunno, 10 times more. Okay, so you may possibly reduce the pressure in the receiving carboy by 15%. At this pressure differential, the wine would be squirting in there pretty good, as if you were dropping it from a height of 5 feet.

In fact, this gives a crude way to estimate the pressure differential. You take a look at the wine coming into the receiving carboy and splashing on the side of your vessel. Try to estimate from how high you would have to drop some water for it to be moving that fast. Take that number and divide by 34 feet. That is percentage reduction of the pressure in your receiving carboy.

So, in summary, I agree with Craig, and do not think there would be much difference compared to normal racking with a siphon.