With a Glock I would say - almost any other Glock is has the same MOA and is going to feel the same - it would especially be true of guns in the same caliber family - ie a G17 and G19.
I think you're hitting on the point of having a consistent manual of arms for your SD gun(s).
I am a beleiver in it. The issue of having your BUG be similar to your primary can be an issue - but there are a lot of people who don't consistently carry the same type pistol on a day to day basis anyway. One day it may be a 1911 type pistol, the next day it might be a DAO with a decocker... So the primary is probably not going to match the BUG on any given day, and the people who have a large rotation of guns probably don't think it's an issue anyway.