Although the damage that you mention is unlikely in any situation, I too had the same type of concerns that you have. I now have the horizontal sleeve and find that it is tremendously easy to handle -- easy to put the Ti in and easy to slip it out. I put my TiBook in with the screen latch down. That way I can easily plug the adapter in while the TiBook is inside the case. I can also see the sleep indicator light when I undo the velcro strap. I don't think these things would be possible with the vertical sleeve. There have been other discussions on this forum regarding whether to put the TiBook in with the screen latch up or down. I personally would rather risk accidentally popping the screen open and waking the PowerBook (only to go back to sleep minutes later) than risk dropping the TiBook with the hinge side down. Therefore, I put it in hinge up, screen latch down.
Regardless of which orientation you choose on, you can be sure that the WaterField stuff is of highest quality. I'm a three-peat customer now (Ti Sleeve, Cargo Bag, iPod Super Duper). Wonderful products, wonderful people.