And what do you think?
I find that for my home brew, packaged with my system and my techniques, and for the taste buds of those that sample my wares, that the bottled samples consistently taste better than the kegged versions. Sometimes dramatically so. (This assumes the beer is otherwise treated the same; that is, force carbed or primed, or cold conditioned the same, same drinking vessel, etc.)
I had a stunning reminder of this just days ago. I made a lightly smoked porter last fall. It was an "improved" version of something I've made a couple times years ago, when I only bottled. This version was force carbed in a keg. I had very high expectations for it; but It was only a good, decent, very drinkable beer. It lacked a depth of flavor, richness, and nuance that should've been there. So I bottled some up recently to give to friends (used a cheap cobra tap-racking cane setup, force carbed). I heard some big compliments back. Surprised, I tried a bottle. Wow. A completely better beast. I compared head to head with a friend who agreed (granted, it was not a blind test).
This is not just with dark beers IME. I noticed the same thing with an English Pale Ale last fall. I could not detect any of the fruity ester smell and flavors that are typical of this yeast; but when I bottled it, they were there, very noticeable, and very appealing.
Assuming I'm not off my rocker, I can think of four reasons for this consistent experience:
1) Oxidation. Kai and others have noted that for big dark beers, oxidation can bring "improved" flavors, or at least the flavors typical of what we expect for styles like dopplebocks. I think this probably holds true for lighter styles as well, within limits. Also, it's well known that oxidation is key for the development of red wine, and last I checked, they weren't using any chocolate malt in those. So a little may be a good thing for many styles.
2) Head space. Someone who has studied gas-liquid physics more recently than me should chime in here. You have one inch of head space in a bottle, say this is 8% of the total volume. You may have 15 inches of head space in a corny keg, and this could be a huge percentage of the total volume. I would expect that volatile aroma and flavor compounds could escape from solution (beer) into the keg head space with much greater ease than in the bottle.
3) Gravity. Unpleasant compounds in a bottle only have to drop six inches or so to precipitate out. In a keg, these same compounds may have to travel much further.
4) Dip tube location vs. top of bottle. You can leave most of the dregs behind in a bottle, but in a keg, regardless of how clear your beer may seem to be, I find it hard to believe that a dip tube located a millimeter above sediment, under pressure, is not going to pull some of that stuff into your glass. Regardless of whether it is forced or primed.
I have of course had better beer in kegs than the bottled version on occasion; but for me, in every one of those cases, I can point out that the bottled version got less favorable treatment than the keg. For example, maybe the keg got to sit all comfy in a fridge for six months, while the bottles had to sit in the cellar at 58 to 65 degrees during that time.
Very interested to hear from others on this.
Unfortunately for my taste buds, bottling just takes too much time so it's going to have to be a part-time pleasure!