Off-shore books all use the same lines. Vegas books use lines that will balance their action.
These days you get a lot more better lines in Las Vegas than all the off-shores combined. Vegas books don't move off air anywhere near what the weak off-shore books do.
Not saying you can't find a good line here and there. Just saying it is probably easier to sit at home and pick off lines offshore than it would be to run around town chasing slow lines.
I thought that Vegas has the offshore lines on their screens so they can spot any "smart money" moves! It would seem to me that they would.