[NANONUTS]

I would like to know where you are getting this $400M figure from, I can't find any info on pokerstars financial affairs on the net.
Anyway whatever profit they are making, if they are using balancing they would be making a significantly smaller amount without it. If as you say they are making 400M and they have balanced software who knows how much of that 400M is due to keeping the fish in the game longer. Alot more than 5% I'd expect as if a fish is around twice as long (or more) he will be paying twice as much rake to the site.

And it is not easy to detect, as has been explained, to investigate and come to an agreement on this you would need millions of hands from winning players, no-one is forthcoming with this data. You would obviously need separate data from different sites as each site would be looked at independantly. Then you would need a group involved in the EV calculation, that includes respected longtime 2+2 posters, so that the result cannot be discredited by claims that it is biased.
As for a B&M casino owner, why would they want to go up against the online sites? The online boom has helped the casinos no end, I know loads of people who have travelled half way across the world to play in Vegas that wouldn't have done so, or even have taken up poker, if they hadn't started playing online. Both B&M and online compliment each other they are not in competition.