Calling strikes from a knee

[ToGreySt]

couple of things, what do you guys think about calling strikes from a knee. it is something that I would love to try, I really like the idea of being sure that I will always see the zone exactly the same way every time. being a new guy, I know I have a problem getting a consistant lock-in mechanism and I watched the CLE-BOS game last night with Wally bell behind the plate and i got to thinking if that was something I could do. obviously I am aware of the main problem that in a 2-man system I do have a lot of ground to cover.

also, as an aside, do any of you call games wearing sunglasses behind the plate, any pro-cons you guys have observed?

thanks,

Joe