Personally I really don't like get blinded by bright halogen lights, but if you can do it so it doesn't blind people...
As for the technical aspects of the question, I think you are right to worry about the headlight fitting. The black plastic mount that holds the right headlight (dipped) beam melted a bit on my Brera with the standard blub on - because some plum had pushed the connector pins into the sides of the socket (i.e. between the metal and the plastic) instead of the middle of the connector (i.e. into metal on each side). As a result the plastic heated up and melted slightly to the point that one pin lost contact with the socket. I went to replace the bulb, saw the problem and placed the connector in properly - problem solved.
But point being, those plastic connector blocks can melt so I really don't know if it would take a higher power kit.
Brat Pack no.8