Dunlop Ultex Jazz III John Petrucci

Firstly this is
a) a very hard and rigid pick,
b) quite a small pick and
c) unusually pointed.

Pros:
Lots of control over dynamics
Very precise because of fine point

Cons:
Not suited to relaxed strumming
Small size isn't to all tastes
Pointed end dulls somewhat quickly
Awkward to find replacements when you fall in love with them and eventually lose them all

Being a Jazz III, it is somewhere between the tiny standard Dunlop Jazz picks, and a more middle of the road pick. The extra rigidity means that any change in force applied (hitting the strings harder or more gently) is translated to force on the strings. Thinner, more bendy picks use up some of this force by bending under the resistance of the strings. This design gives more control over dynamics, but this is potentially a downside too.

If the aim is to produce an even volume across all strings and multiple strokes with slight differences in each (eg when strumming chords), then this pick will make your life much more difficult precisely because it will show up every tiny difference in pick attack. It is also more likely to be dropped if held loosely when strumming because when it doesn't flex, it can potentially bounce off the strings instead of following through.

Overall they take a little while to get used to, but they're the only pick that I and some others have used for a long time. Definitely worth getting one set of to try out