Hey Chiny, fancy meeting you here in the ST forum!
I have a pair of soft Teknic saddlebags, and a Nelson-Rigg tailbag... the problem with these is that though they can be made fairly waterproof, they're not lockable and anyway anyone can just take them off and walk away with them.
I wanted something a little more theft-proof (if there is such a thing when it comes to storage on a bike) and also easier to take with me to motels when I'm out of town. No straps or bungees to mess with on the Givi, just a key and a button and all my gear comes with me.
But I've no problem selling the box and getting something sturdier if need be. I mainly bought it for my camera gear, and that's a good 20 lbs if I'm taking everything. (And I wouldn't for a trip, but I might for a shoot with someone.)
EDIT: I just looked up the Monokey cases... damn they sure do jump in price!