To be honest I'm really glad Infinity is not WYSIWYG. I mean, the guns are so small anyway; I can't pick out an HMG vs. a Combi across the table (admittedly I'm new). I would not want to have to buy (building and painting is the real issue) another model from a unit for every possible option I could use. I'm just like, "this dude's a Combi, this dude's a Sniper, this dude's an HMG," etc. I'll be asking my opponents often "what gun does that guy have?" and expecting them to do the same to me.
When it comes to the fiddliness of having different weapon options for a model (I come from Warmachine, mostly, and that was not an issue in that game), I think Infinity does it best. I (briefly) played 40k and did not like how that handled it at all.