Replying to Big Fat Powder Skis???

So I'm from Australia, we don't get too much deep Powder over here! I get around on a pair of thin, short Park Skis just fine (Atomic Punx)

I'm Heading to Austria & France soon and looking at getting the Faction Candide 3.0 or Maybe even the 4.0, which are really wide, for off-piste, freeriding stuff. I'm Wondering if anyone can tell me how much of a difference it makes in the deeper snow having these huge skis? Do they affect your manouverability? Will the slightly thinner 3.0 be suitable if I encounter some deep pow or Should I go real fat?

Leaning towards the 3.0 but unsure as deep pow is not something Ive really had to deal with before.

I got some knee- deep pow in NZ and the Park skis were hard work, I definitely thought I needed bigger skis, the questions is, how big????

Thanks