Thats true, I could boot off an external solid state disk. But then I have a disk hanging off my computer forever. I tried various synchronization options over the years and pretty much gave up. What I need is a laptop with an "internal disk eject" button :-)
I commuted for years as you mention, with the low hanging backpack. But before that I had it strapped to the rear rack and that felt much better. I never had any problems with my laptop in a padded bag.
These Tailfins I can use for a whole bunch of things beyond commuting, my wife can use them for grocery runs and they will be used on day bike trips. So I could choke down the price with all the things they can hopefully do for me.