well, i think if you need a little more engine, the 1400 might be a bit overkill.. sure its a nice bike, lots and lots and lots of torque, but way heavier than your 500, and much more expensive. The new 1250 Bandit could be worth checking out, too, if the 1400 is on your list.
If your not in love with inline-fours, how about an SV650? I had that bike for 4 years, and it does everything nicely, though maybe the seating was too sport-oriented. If you buy the S-model, with half-fairing, you can even go touring with it. Its not the slowest thing around a racetrack either, handles very well, though its stock suspension and brakes could be better.
I would claim the SV´s engine is quite a bit more than the GS500... but of course it depends greatly on your use of the bike, too. Not everyone likes v-twins, so you have to make up your mind yourself.