A friend of mine had her 883L converted to 1200 this spring, and the difference is night and day. The 883 was her first bike, and the power output was good for her to learn on, but she was having trouble keeping up on the superslab, especially in hot weather and with a windshield mounted. That is all cured now. She had the conversion done at an indy shop and paid about $900 parts and labor, which included new jugs (instead of boring her old jugs). The reason she went with the new jugs was to minimize down time (she would have had to wait for a couple of weeks becuase the indy was farming out the machining work). Probabaly would have saved $100 or so by reusing the 883 jugs.
As stated above, if you plan to keep the bike, it is definitely worthwhile. And as for the statement above that you should upgrade to a big twin, I doubt your 883 + $1000 = Big Twin.