I've always liked short barrels. However, a short barrel might matter alot more efficiency wise for a pump than it would for a mag guy like me. I like running a stubby 8in Armson barrel on one of my RT's sometimes, even with a 68ci tank it still feels like I'm weilding a lil sub-machinegun. I use it for the fun, compact aspect, rather than any performance benefit. That and it's loud as hell! My accuracy isn't as tight as with a longer 12-14in barrel, but range is exactly the same if they both chrono 280fps (despite old wives tales) so no biggee to me. I also used to run a 8in Lapco Bigshot on my old A5 that I ran 'hawaiin style' with my tank reversed under the gun. I had a e-grip on it and a 3-point gun sling to carry it with, and that thing was a fun gun. Deadlywind makes a stubby 8in barrel I thought would be fun to use too.
Tons of guys use pistols with short barrels, and plenty of mil-sim types use Tippy's with real short barrels (some even 2-3in short) for looks and fun. Iv'e seen several pics of people running very stubby Phantom pistol setups on here too. It's just paintball, so if you like it give it a try. You can always swap it out for a longer barrel later if you don't like it.
I think their lots of fun, as long as you don't mind giving up a little in efficiency/accuracy.