The Messenger Ti will probably handle a little bit heavier oil than the Punisher, but the Punisher will probably go longer and snap harder with similar drillings. (The B/S/P Ti pearl will be very slightly earlier than the balck/gold Ti pearl.) If the Messenger is tracked or not highly polished the way it came out of the box, it will definitely be stronger, earlier and handle more oil than the Punisher.
The difference between them is not huge; if I were you, I'd use the Punisher to replace the Messenger Ti OR drill it slightly differently you accentuate the differences between them. Heck, you can also modify one or the other's surface slightly to also accentate their differences.
If the Messenger Ti is truly 6 years old, I think you more than got your money's worth out of it. But, if you like it and it still works well, then keep using it.
Some pro shops really love Columbia balls and some really like Brunswick. In each type of shop, you'll get a different opinion. I like both ball companies. Both balls are excellent when drilled for the bowler and used on the right condition.
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"None are so blind as those who will not see."