I don't think there's a problem with a Jazz pickup sound not being hot enough in metal. It's more important that you get the insane bridge/crystal clean neck contrast done traditionally so well by the Jazz/JB and EMG 60/81 combos.
My main complaint against the 59 is that it is very bass heavy and does not cut through on the top end like the Jazz. But, a lot of people don't like the Jazz because they find it too bland and flat.
Something else to consider is what you plan to do with your neck pickup. Most guys in metal, me included, prefer to solo from the bridge and use the neck for cleans.
Where it gets more complicated is if you want to play warm cleans and solo from the neck. In that case you'll need a bit higher output neck pickup. But, a warm, "pushed" neck sound for distorted leads may not clean up as well as a less hot pickup. Getting this without getting muddy is key. Dave Murray's solo tones in Iron Maiden come to mind as far as a "hot" neck sound, but to my knowledge he's used stuff more along vintage lines (at various times Duncans and also DiMarzio vintage PAF and PAF Pro models).
My most important concern is clarity and definition. So I always try shoot for a slightly less hot pickup than what I think I'll need, and then use the amp if I need to dial in more of something. It would be easier for me to get more warmth from a Jazz with the amp, for example, than to make a 59 more articulate.
In these modern times of almost endless tone shaping in plugins and gear that alters tone later in the signal chain, I'd rather not be put into a straitjacket by a pickup voicing that I don't like. For that reason, I prefer a very flat, articulate pickup as a base line for tone and to add in color with the amp. You may disagree and, as always, your mileage may vary.
