Firstly, edit posts instead of posting new ones. Posting twice in a row may be seen as an attempt to boost your post count, not exactly the most reputable thing.
I like the idea of negative effects on overdose of mana potions. The same thing can be applied to overdose of health potions, which pretty much does not leave either in peace. Perhaps the negative effects could include, other than death, would be what the WoT series know as \"gentling\" for males or \"stilling for females. Basically, the channeler is cut off from the ability to channel, either by taking in more of the magical power than safely handled, or cut off forcibly. Rather harsh, though. As for increasing the weight of mana potions, a mage could simply summon a magical helper of a sort to carry his/her/its mana potions.
As for transferring the \"burden of upkeep\" on another magical object, I would like to see as to how any mage would be limited in their enchantment creating capability. Sure, the mana is lost, but it can be regained like after casting an ice shard or arrow of air.