Yes, the seat will fit '04 - '08.
Corbin: One thing to keep in mind with Corbin is this is a firm seat. It's the shape that relieves the pressure points but still a hard sitting and takes about 1K miles to break in to your shape. Also, to install, many have had to shim the latch with a washer or two so keep that in mind.
Yamaha Comfort Seat: Gel seat, slightly slippery and leans toward the tank more. It doubled my comfort and riding time to about 90 minutes before needing a break. Because it is gel, sun makes it HOT and it stays HOT. Cold keeps it VERY cold. It's not a bad upgrade but certainly not the best.
Sargent: 100% custom. Talk to the rep on the phone. They will send you instructions on how to design your seat and what pictures they need. Expensive but you'll get what you want if you listen to their instructions and design recommendations.
Top Saddlery: Like putting the living room couch under your arse. I've yet to hear from someone who has bought the seat that had a complaint about it. A testiment to their work? Never saw a used one for sale!

I want one but the price is a bit steep for me right now. Maybe next year.
DIY: You have control and can make the seat what ever you want. Time, patience and small adjustments are key. Do all the foam work and test it many times in the process BEFORE you do the final staple job. Make sure the seat is right so you do not have to revisit.
Hope this helps!