Hi John
The Pyrenees is a spectacular place, the lanes are more trails and depnding on what time of year your thinking of going will depend alot on how hard they are.
I'm my opinion generally they are quite easy but take you to areas that other don't see, the wildlife can be amazing and you will see Black Kites, griffin Vultures and other wildlife and if your lucky even a Brown bear and European Wolf, (I have never seen the wolf yet)
to give an idea
if you want some idea of what the trails would be like or to compare i'm not sure where you have been but nothing as hard as say Wales but as in the mountains can be deep water crossings, heigher in June than say August. Also some very steep sections.
There is some things you have to be careful about
1. if you go into Andorra and leave via a trail you WILL be stopped. they have hidden lookouts and I have been stopped ever time by Spainish customs.
2. The spainish side is better to drive than the french side.
3. Spainish law means only 4 vehicles in convoy, (900Euro fine per vehicle extra)
4. In spain they don't speak spainish in the mountains they speak Cantonesse, this is confusing at first.
5. You can Wild Camp in certain areas but only if 5km from a road, this will depend on where you are.
I wouldnt advise going on your own in 1 vehicle, you can travel all day without seeing anyone, or it can be very busy there is just no telling
one last thing is it can be very dusty and a replacment airfilter is not a bad thing to take.
to give you an idea this is a video from my trip last year
http://www.youtube.com/watch?v=yg3Q45WMwDIthe highest we go is 8000ft which is the picture at the foot of this post
regards Gary
PS I was with another club and offered to run a trip there but never got any interest so dropped it, I would offer to run one if there was any interest.