I am a hardcore tournament player who has played in Rogue Trader Tournaments from Salem, Oregon, down to San Francisco, Sacramento, Los Angeles and San Diego, California. I have also played in Jacksonville, Orlando and Tampa, Florida. Right now I am playing and living in Phoenix AZ, but the tournament scene is rather dead for a city of this size, so I might need to join a league.
I try to attend as many large tournaments as I can. Although the GW Grand Tournaments get a bad rap, I enjoy them, and my goal is to win a GT one day. Also I attended Adepticon in Chicago every year and if you are a fan of 40k, this is a must because there is no other event quite like it.
I see a lot of people talking about WYSIWYG and wondering if it is ok to play at tournaments without being 100% WYSIWYG.
Is it ok to use spinegants for termagants?
Is it ok to use a power weapon for a powerfist?
It is ok to use X unit for Y unit?
Here is the truth: Tournament organizers normally don't care, and most of the time neither will your opponent. The only time it will ever be an issue is if you get the wrong type of opponent and you start to beat them. Then all of a sudden WYSIWYG will be an issue because then he will start to complain about your models and might have the TO come over to do something about it.
As they say in boxing, 'you must protect yourself at all times', so just as a precaution, you should always be WSYWIG as much as you can, and when you can't, talk to the TO beforehand, and clearly explain to your opponent before the game begins what is, and what is not WYSIWYG.