I've been using velcro strips for years now. They work! And I haven't had any problems with velcro catching debris at all.
Re. the FlexAir pillow... I've used them before but discarded them. YMMV, of course, but they are relatively uncomfortable to me, they make quite a bit of noise, and of course, they don't last all that long (would hate to apply new velcro every "so many" trips.
If you haven't tried it already, I highly recommend MontBell's air pillow. It's built with different air chambers (so when you lay your head down, air isn't squeezed away to all other parts of the pillow) and designed to 'cradle' your head (and still works well with side sleepers like me).