Just received & fitted my SW-Motech Daypack tank bag which I bought at the NEC Bike Show at the beginning of the month.
First impressions are that it is sturdy & well constructed.
Fitting was a little involved, requiring drilling through the base to locate the mounting plate. This allows you to place the bag wherever you want within a certain range on the tank, ensuring it doesn't snag with the handlebars etc.
It's a small bag but that's all I need to keep a few bits and pieces in for my commute (puck, visor wipe, waterproof jacket neck seal etc).