I have had two years of being paid by US company while in the UK and painful does not even begin to cover it. Initially I got airmailed checks (cheques) and would pay them into my UK branch who would promptly send them back to the US for clearance. It took one payment five months to end up in my account. Seriously.

We fixed it and started using wire transfers which worked fine but I would get beaten up on the exchange rate. I was one of the few people in the UK hoping our economy would get worse just to improve my rates :-)

I would say the biggest problems were

- W2 withholding (they had to have proof I was legit or they withheld taxes and payments)

- not having a US bank account

Getting a US account is on my todo list, but it was so problematic (my UK bank simply refused to help - less than 2million GBP turn over ? Fuck you, work it out yourself). There is a Silicon Valley bank that is more amenable but by the time I found them we what wire transfers sorted and it lost it's allure.

So until I am likely to do a lot of small business in the states, I am sticking with "wire me the money - or I don't work"