Nice little article and fine result. I have some slight disagreements though as I think tips for competitions is a thing open for discussions.
First the contrast bit. What is seen in a GD competition through the glass is contrast between colours and brightness. You can get away with less actual contrast if you keep that in mind. And even so a lot of more subtle stuff has won too, you just got to get noticed in some way. If you have a subtle style - sure go for it. But I wouldn't advice to push contrast everywhere for everyone. Too much white and black might instead lend the miniature a washed out feeling IRL while it looks good on photo + technique and getting everything smooth becomes very very difficult. If you are not an absolute topclass painter you will make mistakes and they will get noticed.
And no you don't have to use the EM style... not even a very super duper clean style (I am a collector and have bought GD winners and seen lots more) It can help in the Opens... *nudge nudge wink wink* but otherwise as I've said I've seen lots of different styles getting a trophy. It is not worth giving up your personal style for a better chance at winning a deamon. A tip I would give though is perhaps a similar in some way but still different:
Try to use GW's world and artistic direction as the inspiration for your work, look at Blanches work for example and make your own version of it. Doesn't matter if you edge highlight like the Eavy metal team just that it feels like something that belongs to the Warhammer universe. That is the single most important thing to keep in mind I think.