I work in the 'ramp' environment, hearing protection is a daily issues in our workplace.
I would just make one comment, it may be obvious but it IS often overlooked.
With any 'in ear' protection your standards of personal hygiene need to be very high. It may sound like a no brainer but it really is important. Your ears a very sensitive and delicate organs if you are going to insert a foreign object which will remain in place for hours at a time, you need to be sure they are clean ...
On the ramp where hearing protection is used/removed on a frequent basis we tend towards 'on ear' protection (in preference to in-ear) simply because the working environment is not conducive to high standards of hygiene for removal, storage and refitting of in-ear devices.
Please don't get me wrong these in-ear devices are great but just remember the hygiene aspect of their use.