All in all I have to agree.
Although he is limited by the high number of players in play, if it's the case, cause he may be far from his direct target and may need a blue card to attack, it looks not enough to justify the 5 lifes, IMHO:
- when he is near to the target he is obviously too strong;
- when far from the target he still may choose between two good strategies, -1- charge himself drawing 4 cards (incredible powerful with expansions), -2- play the blue card to shoot the target (who may need to discard it to save lifes, so we come back to option -1-) still having the advantage of 5 lives/5 cards which compensates the "forbidden" cards (Mustang and Barrel).
We know Bang! is usually "self balanced" by roles and by the perception that players have of a character, besides the average power of the characters is increasing year by year; however I still prefer "self balanced" characters too.
I think it may work great with the same ability and 4 lifes, he would be still dangerous but would have to care of defense as well.