Im not a big fan at all of bitter beer so will probably be chilling just to be sure.
Mornin' Truman,
Try to think of it from the other way around. Don't think of chilling as a way of lessening bitterness. In the same way don't think of no chilling as adding bitterness. As mash brewers, one of the things we strive for (among many) is consistency from one batch to the next of any particular recipe...Think of whatever method of chilling you use as "your method" and adjust your hop quantities or usage times to suit.
Hope this makes sense.
Even though no chilling a beer increases the potential for added bitterness, people dont "no chill" to deliberately increase bitterness, if you know what i mean.
I have been a chiller, and am currently no chilling, and i've had to slightly alter my previous recipes and save them as "beer beer beer beer NO CHILL VERSION" or something like that. Once your recipe is in perspective of your chilling method, your beer will be so close to the original chilled version you'd be hard pressed to notice any difference.
Brewers that no chill, often do so for other reasons that have nothing to do with hops. For me, it's the convenience and water saving from using a chiller. I'm not setup to recirculate and reuse my chilling water so it's much easier for me to "no chill". It suits my brewing lifestyle and time constraints. It means i can brew like a bastard when i have the odd weekend off, fill my cubes with wort, and then ferment them when a fermenter becomes available. For me, no chill is all about convenience, and i've adjusted my recipes to allow this method to get the same beer as when i was chilling.
There are many ways the no chillers get around "locking" in hop flavour and aroma that is the signature of the chilling method. It can be done, and it can be done easily.
There are numerous threads about how to adjust hops to compensate for whatever method you settle on, and this post from me alone will probably open the obligatory can 'o' worms, but do a search, read heaps, and as always, continue to ask questions.
Happy brewin'
Nath