I have an
IG army that is pretty much brimming over with proxy weapons. I have used this army for years and even in Rogue Trader tourneys when
GW used to sponsor them. I have never had any models disallowed and very rarely has anyone complained about the unconventional models. The theme is an undead traitor army with a lot of troops and gear scavenged from the battlefield.
For example here are some dark eldar that have been reanimated. It is not hard to tell who has a lasgun and who has a heavy weapon. I have now 60mm bases for the
HW teams. When I started this army it was before
IG HW teams were mounted on big bases.
Here is an example of a scratchbuild for special weapons that I use and no one has ever objected to them in tournaments or casual play.
Oddly enough I did have someone object to these Missile Launcher models. The thing is, these
ML are honest to god
IG/
SM missile launchers and the
TO told my opponent not to bother him with silly objections.
Two of these troops have boltguns from the beaky sprue but no one has ever complained about them representing lasguns.
I suppose how people react is always going to be unpredictable but as long as you are not modeling for advantage and there can be no confusion over what is represented, reasonable people are not going to object. I expect some day that perhaps one or more models could be disallowed in a tournament but if that happens I will just deal with it at the time.