Why would one thumb stretch further typing in landscape? Usually, when you're holding the phone sideways for typing, your thumbs will be coming up from the bottom and not stretched around from the sides. So an off-center landscape screen shouldn't affect typing unless the slight imbalance bothers you.
By the way hal1, speaking of the Droid, I was just at Fry's today and they had a display up with a Droid. Now, it was just a dummy phone, didn't work, but the body was legit, and the slide mechanism seems really loose and floppy, and just from using that display phone, I don't think I'd trust a Droid to hold up. Buuuut, it was a dummy display phone, don't know if the hardware is completely identical to the real thing, and it probably gets slid opened and closed a lot, so I was wondering how your Droid is out there in the real world?