There are so many cool uniques in the lower levels which are not viable for endgame because they cannot be brought up to endgame item level. I wonder if and what gamebreaking situations could occur if they could be nanoed up to max item level. I had leveled alot of low level uiniques to their max level and they were still very underpowered in the late game so i am not sure if there are any that would break the game.
One problem could be that some weapons become totally overpowered and another would be that some rival current endgame weapons which would be good but it would also mean the possible need to farm low levels for that weapons. On the other hand we did farm Gnippi alot.
I think it would be worth testing.
These are the weapons that would very interest me with what happend if they were max level. They are unique guns that have a special affix that is above the norm (eg increase damage 50%, double the rate of fire. huge spalsh or field size etc):
Double hestias vision would be fun