I dont know what has been changed in invisibility, since ambush was tuned, but
it doesnt feel too reasonable since it kinds takes away the idea of
invisibility when majority of agressive monsters see you anyway. So... I dont
know if sneak skill has been counted into account or not, if not, maybe it
should. Invis people do make same amount of noise as they do while visible,
but sneak should reduce that yes?

It's not a good idea at all to start mixing different senses to vision-only
thing. I don't recall players having the change of 'seeing' invis foes by
hearing or sniffing them out (not that it's really an issue since mobs are
there to kill you, and will attack on sight).
But if you're invis, you're invis, no reason to say 'yeah that ogre-dog can
smell your pants you haven't washed in a week, so quit whining, it doesn't see
invis but it smells invis!'.