You appear to be a vendor. It's pretty quiet on this forum. It would be helpful if you put your location in your profile along with some more details about yourself. It gives context to your posts and may get more interest in your products if people know where you are located.
What has you thinking about moving from the Suzuki GS500E to the Fazer 600? Naked or faired? The Fazer has rather more power. Both are standards, though the Fazer is a little more sporty, aside from the naked version. The engines have different characters. The parallel twin of the 500 doesn't rev quite as quickly as the inline 4 of the Fazer and the inline 4 has less compression braking on decel.
Some consideration for your riding experience and how you will use the bike should be mentioned as well.