For $300 BlackBear will Data Log tune your truck. I don't think thats very expensive at all. How much is a handheld like the Diablo, which is supposed to have good reviews. $250 or something? Basically any review I have read from people who went from a handheld to a custom tune noticed a difference. So there are chips, then comes the handhelds which are probably noticeably better than the chips, then the custom tune, which appears to be noticeably better than the handhelds.
For what it's worth, I didn't notice much difference in performance at all when I did a K&N CAI and catback Flowmaster 40. However, after I did the tune, I noticed a somewhat significant gain in performance/driveability. It doesn't burn tire, but it sure is much more responsive.
Last thing I'll say, does anyone have a comparison of before and after a chip/handheld/tune? Before my tune, I did 30-90 in 20 seconds, after tune I did 30-90 in 15 seconds. That is a pretty solid gain in my opinion. Sit there and count out five seconds. It's rather significant if you think about it.
Go with a custom tune man, it is worth every penny.