Suxuki2000, I've been using tank bags of various types for years. The kind that have the little straps that you have to position and tighten on the bottom of the tank every time you put it on or take it off are a real pain. It makes every gas stop a hassle, plus they move around a bit during the tightening and settling in process, making scratches a possibility.
The early magnetic types were susceptible to tank scratching because the magnets weren't strong enough, which allowed the bag to move around.
There is a 3rd type which consists of a semi or full coverage tank cover(bra) which stays on all of the time, and which has snap on attachments for a non magnetic bag.
I'll dismiss the strap type, since I think that anyone who uses one is a masochist.
Aside from the wax, which is a good idea with or without a bag, the secrets to using a magnetic bag are:
1.Get one that fits the contours of your tank, so it won't try to reposition itself.
2.Get one with strong magnets and good padding on the bottom.
3.If you live in a rainy area, get a bag with a built-in cover.
The best magnetic bag I've found for the Busa is made in Germany, and is made by BUSE. It's made of a Cordura type material, has several external pockets, a built in rain cover, strong magnets and an internal stiffener which holds its shape whether full or empty. It has large flaps which can fold and velcro flat when off the bike, and backpack straps for carrying. It also has a strap on the front which snaps onto the front of the tank and is adjustable. When installing the bag, this allows you to position that strap, pull back on the bag, and drop the flaps into place in the same place every time. It is so solid you can lean on it as you ride. It also has a nice feature for whenyou only want a very small amount of carrying capacity. The main bag unzips from the base, leaving only a map pocket and the compartment for the rain cover. Those compartments will hold a few small items without the usual bulk of a bag.It is fairly expensive, at about $160.
The 3rd option is best represented by the Bagster, a French company. It is a full coverage tank cover, nicely made of an imitation leather, and has attachments for a variety of bags. Dirty Pete has posted pix of his. I think the cover is the slickest thing I've seen, but haven't found a bag I like as well as the Buse, although I haven't tried them all. Of course the Buse will still work with the Bagster cover in place. The Bagster cover is about $170. and the bags range from roughly $100. to $150.
The only real downside to magnetic bags is that you need to keep your credit cards etc. away from the magnets. Hope this helps.
[This message has been edited by SlowHand (edited 05 March 2000).]