metatrader can hardly be called "professional". Get real for a second.
Depends how you define "professional". If a professional trader is someone who takes their sole income from trading then you can count myself and a few other people I know as professional traders who use metatrader. There are a lot of people who are very sniffy about it but have either never used it or didn't use it long enough to work out the value of some aspects of it. As for spreads, yes, spread betting in the uk usually means you pay more spread but I compared my dax spread at 0.8 fixed with Oanda with a guy trading futures and by the time he had paid commission the cost of trading for him was 9 ticks so who is better off? At the end of the day it doesn't matter what platform you use it's all about the money.