I wouldn't load that ebay one up with stuff and put it on my back! (Unless I was only going to fill it up with bubble wrap) When I go away for the weekend I use a normal holdall. In this pic I have quite a big holdall and a rucksack. Strapped together very nicely. Used the rucksak straps under the undertray and the strap from the bag. Rode 120 odd miles with no problems. Maybe go for a normal bag that you could use off the bike too. If you get a pointy you get free bungee hooks!

Shot at 2007-06-29