Jeff is correct, Fly 18 pads are strictly temporary hole pads. It's a lot of money to spend on pads for designing a course.
I bought a fly 18 pad for my backyard and it has never got mud on it yet it is completely clogged and water does not drain through. This is after about 4 years. If I pressure washed it, it would probably drain again but they will eventually clog up unless you pressure wash them regularly.
Once they clog up they become a giant puddle.
These rubber pads really only work for temporary tournament holes during the summer. You see them on courses at Worlds when they need to make a few holes longer etc. Once you track mud and dirt on them they are pretty much useless.
I was in AZ at the 2013 Memorial shooting video and they create a lot of temporary holes to make the standard courses more difficult for the pros. The pros were allowed the option to throw from either the Fly 18 pad or directly to the side of it.
I only saw 2 players throw from the rubber tees during 3 rounds of golf. And this is in AZ where there is no moisture or mud or any chance of slipping.
There is also a video on YouTube from disc golf live of the 2011 Amateur Championships in MI and there is a scene where the lead group is teeing off from a Fly 18 pad in the rain.
Take a look for yourself before you make your decision, go to 13:15:
I think the concrete paver method is the best for designing a course and still having the option to move the tee.
Andrew Rich installed astro turf covered tees at Alton Baker park in Eugene. This is a step in the right direction. I am a big believer in astro turf tees. With pavers you usually have a pressure treated lumber box around the pavers and this would allow screwing down a layer of astro turf on top of the pavers.
I have not gone down and checked out the astro turf tees at Alton Baker yet but I have a feeling they are awesome!