"So in reality I don't think the rubber between the barrels has anything to
do except stop the free floating barrels from moving."

The problem with the rubber inner tube between the barrels is that it makes the rifle look like it came from the Wal Mart toy department.

As for regulation, reports are that some of them show up at customer locations not regulated worth a crap. But the set screws at the barrel ends can be used to regulate the gun to shoot almost like a bolt gun at 100 yards. Not many doubles can do that.

Personally I vote for Blaser to solder the barrels to a fixed rib like any other double, install a real safety instead of that cocking thingie, get rid of the scope base divots, lower the comb for iron sighted use, and install a traditional shallow V rear sight instead of that contraption that some young German engineer thought up. Then at US$8K the Blaser would be a good deal and I would be very interested in buying one. In its present form, I would not want to hunt with one.