It's a good deck, but if you're going for extended anyway, why sigma? Why not go for some hard hitting 5 star or the plethora of good 4 stars sakhrom has?
Since you are asking the general public:
My view on any deck involving Ambre is "lame". Ambre is a giant crutch, and using her undermines your ability. Every time I see an Ambre deck my first thought is "lame", followed closely by "I bet this person doesn't know how to play without Ambre".
I'm guessing there are many people who disagree, but this is my personal opinion on Ambre.