End of the day it all depends on what you are trying to acheive or show and also as the above post mentions who for.
Granted really heavy maille will take the blow out but then what does this really show. When I started looking at the weights and gauge of original maille I was rather surprised how light some of the stuff was, the first real maille shirt I picked up could also be picked up with your middle finger.
In fact this is one of the reasons why we started doing the 18gauge round ring both for early period and late C15th as it seemed much closer than the 16gauge stuff around.
As mentioned earlier, maille does appear to be a composite type of armour, examples of padding with 25 layers of linen amongst other things being cited for one. I wonder how many gambesons around are constructed like this, certainly its one factor that seems to get missed, yes I appreciate for early periods the jury is still out on this one and I am sure will be for some quite considerable time.
As far as how light can you go I think we also need to consider the general look of maille when it's used and in what context, certainly comparing butted vs the riveted against original examples, the way the butted hangs is in my opinion significantly different. The Aluminium looks odd that's for sure, as does plastic.
Having recently seen Henry V at the Globe with the actors wearing plate but alongside this what looked like knitted maille. ahhhhhhh but that was just my cringe moment, im sure the majority of the audience didn't notice. Incidentally, I still enjoyed the performance despite this.
Personally I think as long as we are aware of the inacuracies and don't try to hide the fact. (I still hear comments of look how heavy this, as a split ring washer shirt is given to a member of the public) Then I think it all boils down to, as I said earlier, what you are trying to show or what you are doing with it, certainly people should not expect to go into a melee wearing plastic armour against metal weapons and think they are going to walk out bruise free. Although I guess that's much the same as wearing anthing come to think of it.