I used to wear my Rab gaiters over my trousers but I've stopped doing this, for me, often a guaranteed way of getting wet feet! The one hiking stretch I remember most is that section between Alston to Garrigil, can be very wet grass on an autumn morning and after rain. Nowadays, I always wear my gaiters under my trousers and in the main I have wet feet no longer. The Glynder's Way also has a wet grass problem and when I walked it, there were lots of it!
My Rab's are designed for outer use but they leave an elastic mark on my skin if wear them against my skin for too long, so I am now looking for a new pair. I may or may not buy Rab's again? None of the makes seem to be designed for under trouser use so I will get my wife's friend to fit some soft fabric over the elasticated tops, or maybe I'll wear long socks and fold them over at the top of the gaiter?
I know that my trouser bottoms get wet very quickly, but they dry very quickly as well. The inside bottoms can get muddy as well but I have an easy solution, I just use a nail brush to scuff the dirt away.