I think the effects work on 'Q Who' still holds up! If they just rescan it in I think think it'll be rad. That episode just *works*. I don't think it needs to be massively improved.
There is much to be said for minimalism...especially in an episode like that where the stoic, terrifying solidarity of the Borg is communicated perfectly by how little effort they actually need to expend to control their prey. I think "flashing it up" would really undermine the quiet tension of this episode.