I would NEVER use lemon juice. The Lemon wedges are shaken with the alcohols
to give it the lemon flavour. Always fresh fruit over juices.
No idea what "Simple Syrup" is but it sounds awful. I'm assuming it's a brand
of Gomme, in which case I would definitely not add it to the mix. Gomme and
Sugar syrups, in my opinion, should be used as sparingly as possible and only
when using real sugar isn't possible. I wouldn't put sugar in a LIIT, and I
wouldn't put gomme in either.
As for the layering, it looks brilliant and when the customer gets the drink
they move the ice which mixes the drink anyway. Good looking drinks = repeat
custom, happy customers and tips. Win win in my opinion.