Depending on height of fall and hardness of contact surface, I'm not sure I'd bet on a pane of glass in any case, but the Blurex's corner-clips do hold the tablet with some serious authority. It'd take some funky, but not impossible, physics to pop it out.
The bumper case you linked to looks like what I had in mind before going for the Blurex offering. I figured the small form factor made the A100 more like a reach-for-it-and-go phonelet than a full tablet, so I wanted a hard, snap case with no flap to contend with. When using the tablet in portrait, I'll occasionally get annoyed with the folded-back flap, but the more complete protection and premium/professional appearance/feel of the Blurex case more than make up for it.