[Closed] 1x11 chainline advice

Hi,

So I'm looking at options for a Shimano XT 1x11 upgrade as a Christmas present and am wondering about crankset and chainline. I've a perfectly reasonable Shimano Deore triple crank (currently with a granny, middle, and bash ring) that for cost-saving I was intending to keep, and just put a new chainring on it. But, would the chainline be acceptable like that? I see that if I go to the XT 1x11 groupset builder at Chain Reaction they offer a choice of 50mm or 53mm chainlines. Surely the choice of cassette doesn't make a difference here, so what's the point of this choice, and would the middle ring on a standard triple crank be acceptable?

Cheers
Ross