With the old xp system and no upkeep it would have been terrible idea, but things have changed with the patch. Right now there is really no way for anybody to constantly upkeep plate armor and other more expensive items. System like this, what would also reward players for for their personal kills actually might have it's benefits.
Some of the more skilled players could actually afford more expensive items and with the upkeep, others would be forced back to low-medium gear, with new xp and gold system it is a lot easier for other players to catch up so there would not be just few veteran players slaughtering everybody. You should not really be able to make loads of cash with it in higher gear, just give you a chance to get barely enough money for upkeeping your really expensive gear if you keep up the good performance. The more expensive gear you have, the better you would need to perform to constantly upkeep it. (Obviously it would be easier to get kills in better gear)
You would be able to stack up gold a bit easier while playing in lower level gear but you can pretty much do it already, just takes more time (this would also make it easier for other player to catch up to those who already have better items). It also might remove some of the naked leechers when you can actually get some rewards for kills.
The reward for killing someone should depend on their level and total worth of their gear. (don't know if you can actually implement the last one) We would also need to have TK penalty again.
Ofcourse there would be problems with this system. Players would just hunt for kills, not caring about their team and i don't think it would actaully work out that well in the end. I personally just don't see that many options to make some of the players actually be able to get higher gear while not making everybody able to use it.
