if this goes through, it is going to take a few weeks for the whole thing. tease...I know, but I am looking forward. , more later.
The standard Sidi genius is a bit narrow for my wide feet to go in comfy for a long ride. I have tried the "mega" version of the genius and those fit me well. To give you a relative size comparo:
Sidi genius 5.5 42.5 std, tight,
Sidi genius 5 mega = good fit;
Sidi Ergo1 42 =good fit
2011 Northwave Aerlite SBS, 42, excellent fit,
2011 Northwave evolution SBS, 42 = good fit;
2011 Fizik R1 41.5 = good to very good fit
So you can appreciate that the big conundrum of cycling shoes is that even between models on the same brand there is variance.
In terms of stack height the sidis with speedplay adapters, have the less ammount. The Fizik the more amount of stack. My favorites are the Ergo1 and the Fizik in terms of the quality of the ride.
I thought twice about posting all this, since shoe fit is soo subjective, but I figure, at least the relative ball parks will help you.