The C5 has 18" wheels front and rear.
G5 has 19 front and 18 rear.
C5 has a lower seat height and has a nice feel on the freeway, solid, almost lazy cruiser like steering, but solid. For a newer rider or someone who putts a bit, this gives a lot of confidence and warm fuzzy feelings.
The G5 feels like a Yamaha 650 twin from the mid/late 70's. Handles very nice in the twisties, has better ground clearance for spirited riding, awesome brake for when you ride too quickly. With the slightly shorter gearing it has a bit more oomph from a stoplight. When in the twisties, it doesnt really ride like it's looking for a fight, but half wishes one would pop up.
You need to ride both and buy the one that suits YOU.
If your local dealer doesnt have 2 demos to ride, drive to Fresno, ride both, and buy the one that makes you grin the most.
I'll do something for your time and gas you spent should you buy one here.
Dont wait too long as the first 100 are getting low.
Big Al
BMW of fresno