Does it matter any longer which exchange things are listed on? I can trade any stock on any exchange regardless of where it is. I guess only trading hours and holiday schedule would make a difference.
At volume, the stamp tax on UK stock would be significant.
More fundamentally companies tend to be valued higher on the US exchanges, which gives companies a bit more freedom of action to raise capital from the market to fund their plans.
I don't think UK Gov will cry too much abount RPi. They certainly would be leaning hard on the board of, say, Shell, if that corporation decided to list abroad instead of London (as their former CEO has mooted).
US has very strong and deep capital markets. There's a reason New York has been the financial capital of the world for the last 100 years and will continue to be for the foreseeable future.
