It's easy to change but time consuming. I changed my taxiways to gravel and the aprons to brick. Only the asphalt is effected by the GW3 textures. I also added additional parking, a 20 plane AI file, and an eye candy file.
One suggestion for those making scenery, please don't hit the (all) button when making an exclude file. This makes effects inoperative such as smoke, etc. If there is an effect you need to get rid of, a small area should handle it.
Ian, if you would like these files I'll send them to you then you can use, upload, or scrap them, your choice.