Do you have one? If you do what kind is it? How much stuff does it hold..Also do you have a tailbag?

 

I had tank bags on my other bikes, their ok if you don't want to cart a lot of gear. reason being, the more stuff you put in em the higher the bag, the more it gets in the way, ok for long boring trips when you can lay on em.
So I end up just strapping em to the back of the seat. I cart my gear around with a bike rack and bags that zip together when I need to cart more stuff. the rack comes in handy for carting larger items, like a carton of beer. The bags come off quickly, and don't seem to affect the bike (although any extra weight always does)
The big plus with tank bags is their easier to fit, the down side is that many can mark your tank, so its a good idea to see wot sort of protection they come with for that purpose. and depending on the type of fitment, they can be a pain in the **** when it comes time to refuel. Oh one final whinge, tank bags usually come with nice clear P.V.C flap on the top, so you can put your map in it and keep an eye on where your going, the PVC must be hypnotic, cause most riders that use them with the map can't ride 3 feet without having to refer to it, and nearly end up as a decoration on the back of someones bumper.