Just on the weapon range aspect, there are times when I wish melta guns, shotguns and flamethrowers did have the same range so that they were viable for my style of play.

Strangely enough, I don't see flamers, shotguns, melta or melee weapons hitting at same range as guns/heavy weapons. To be honest, claiming that ARPG have a standardised range for all weapons is wrong. They usually have same range for weapons of same class, but I never saw an ARPG using same range for all weapons it has. Even in current game you are outranging any melee /flamethrower enemy, but that does not remove danger in the slightest. Same goes for Sniper rifles - there is no reason why they shouldn't fire at longer distance than other weapons.

Thank you for overview!

Personally, I don't like the range of Sniper Rifles. They are exactly the same as autogun/boltgun/lasgun. Turns them in glorified battle rifles, not actual sniper rifles.