Is a tall mountain-bike rider also less stable?

After a good fall from a bike, there's always some opportunity to reflect on what went wrong and why it happened in the first place. While the main reason for my last fall clearly was “lack of attention,” I also came to the conclusion that unlike a smaller rider, like my wife, touching the ground with my feet, for added balance is much harder for me or anyone who is taller or just has longer legs. The center of gravity is pushed up too and makes for a more tenuous stability.

Perhaps the answer to that is a slightly different bike with 29' wheels instead of 26' that might minimize the risk of flying over the handlebar. This tiny bits of difference can all add-up when things don't pan out the way they should and make the difference between a safe recovery and a hard, bruising spill...