Interesting, one person I saw on a wevsight gave it a very good review after putting it in his Martin.  I can see that in my Legacy, someone buy it first and tell us.

Steve

I've sold a number of these to varying opinions. Some say it has an enormous difference, some say no difference, some say it's great at feedback but doesn't affect the unplugged tone much. I think it depends on each individual guitar, as well as the preferences of the individual.

I tried one in a Baden A style with cedar/mahogany. There was a noticeable change in volume, sustain, clarity, and tonal character. Whether or not any of this is an improvement, however, is up to the individual.

Justin installed one in his "project guitar" - an Epiphone that has had all sorts of things done to it. He said it made a huge improvement.

A customer in my shop, after hearing my explanation of it, compared it to a resonator cone. Clearly, there's significant differences between the two, but, to my ear, there is a somewhat similar tonal characteristic produced. My girlfriend's daugther is learning slide guitar. She has a beater guitar that I set up with heavy gauge strings for this purpose. I'm going to put an O Port in this, but I'm expecting it will produce good results for what she's seeking.

A few other notes:

-Be careful with the installation. It looks rather harmless, but the potential to scratch your finish exists.

-Definitely take off all the strings when installing.

-It won't work on Emeralds because of the inward curvature around the soundhole on Emeralds.

-It won't work with many guitars that have on-board electronic systems because the preamp and/or battery get in the way of the O Port's inner flare.

Greate info Michael Stone.  Thanks.

Planet Waves does have a demo video.  You CAN hear a difference mic'd.  Not sure that it's a "better" tone.  To me, it took some of the 'warmth' away...but that's a personal taste thing, AND it IS a video.  He also shows a great way to take out all the strings from the bridge without un-stringing--capo the guitar at around the 3rd fret, loosen the strings enough to pull them from the bridge.  It makes putting everything back very clean and simple...and the technique could be used for fine tuning that pesky saddle

If it truly works against feedback it would, if nothing else, look much better than a soundhole plug, and you could probably hear the guitar acoustically better.  

Certainly would like to hear others' thoughts.

For $28 it should walk and talk.  On the Youtubes that I looked at it did nothing.  As for feedback compressor I have been using on my CA's (High Gloss) a round piece of clear vinyl .35 mil cut the size of a CD that sticks to the gloss finish over the sound hole.  You can buy it by the yard at Wal Mart for $3 a yard you could do dozens upon dozens of guitars and make pick guards to boot. 

I am not a big Planet Waves fan.  Some of their stuff is a rip off.  Starting with thier Humidipak humidifer thing.  I put them in a couple prized Martins.  One a 65 NY'er.  I went to play them both packs had p#$$ed/ leaked a bunch of jell stuff all over the inside of the guitars.  Goes without saying I freaked out.  Thankfully I caught it before the crap dried and was able to remove it all but a few stains.  A guy at coustomer service said he didnt appreciate my choice of words in my email and was so generous enought to send me 2 of the $14 pieces of junk humidifers you stick between the strings that contains a postage size piece of sponge that is dry two hours after you put it in the guitar.  I later discovered Oasis humidifers that are a real product.  While I'm on a PW rant their sound hole feedback buster is the uggliest thing you could stick on your guitar.  Would been nice if they would put all their raised letters crap on the inside instead of plastered all around and over the outside.  Althou it works I just could not bear to put it in my Legacy.  I took it out and by accident I discovered the Walt vinyl sound hole cover that is transparent for the most part.

Re: the guitar humidifier comments Walt...and THAT'S why all my acoustic guitars are now carbon-fiber.

I LOVE the Planet Waves Headstock Tuner...it goes in my "...since sliced bread" Hall of Fame.  I have 3 of them and always keep one in my pocket for music store forays.

You got that right.  Every day I open a case and theres no cracks, swelling, shrinking necks, and other issues I go "Yeah baby"

Ha!  I will admit I have to have one of those tuners also.  I used a buddys and it was dang nice.  I dont capo but thier capo is slick.

I've lived with several headstock tuners.  The $30 Korg AW2G is the best I've owned. 

For a stompbox tuner, the $90 Korg Pitch Black is the bees knees.

Planet Waves is a mixed bag.  Their cables are quite good, and I use their string winder/cutter and their dual action capo all the time. 

I no longer buy a guitar without an onboard tuner.  The one thing I always hated about nylon string guitars was the ongoing tuning process.  Having the tuner on board makes life much better.