I have been doing this and bought a few computer components with BTC, and I went to buy some more components with BTC and then stopped myself because of the 5-6% premium for using BTC. The UK has a very efficient payments system created by the banks, so the incentive to use BTC here is less than it is in the US. I can transfer money between accounts here for no fees, pretty much instantly, even between different UK banks. I will continue to invest a small amount per month in BTC and just hold it until the incentives change (if they ever do).
A company will end up saving money when they process a bitcoin transaction over the cost of processing a credit card or a fiat based transaction, so I don't see why any rationally acting company would ever discourage people from paying in bitcoin in the way of higher prices