Follow-up for those interested-
Completed about 300 miles from Edinburgh in a clockwise loop through the Highlands and back to Edinburgh.
Started out trying to follow the National Cycle Network routes but soon bailed from that. The NCN is a fabulous concept and useful to many but I struggled with the random nature of the cycling conditions. Although well marked it's still very tricky to navigate along them through the big towns...lots of back streets, canal towpaths, parks and random turns. Very slow going. In order to cover 100 miles per day I eventually found it easier to use the roads.
Also the NCN routes I followed often run along unimproved roads, sometimes Jeep tracks, and totally unsuitable for a road bike While using roads I caught up with parts of the NCN here and there and some of it was fine for my skinny tires but once the route veered off into the woods I would pick up the nearest "B" route. "B" roads are much better for road bikes...mostly nice country lanes with light traffic.
I was excepting the NCN routes to be like the ACA routes...good cross country routes for the distance cyclist... but it seems it's geared toward a totally different kind of cyclist..much like riding on your local recreation trail. Once out of the developed areas the NCN routes were very nice in spots but not what I was expecting. My mistake I suppose.
In the Scottish Highlands there are many great climbs if you're into that sort of thing and pretty good but slow descending on the narrow roads. Gotta watch out for the numerous loose and very sharp rocks washed down from the most recent rain and sheep everywhere including lying in the road.
All in all a good ride with some scenic villages and nice places to overnight Got wet here and there and overcast nearly the whole ride but generally dry Best part? A nice pint at the end of a long day. Worst? Several pinch flats one day due to many sharp rocks in the road and sheep poop all over the tires during tube changes.
Haggis with neeps and tatties make a nice meal at the end of a long day.
All-in-all I recommend riding in the Scottish Highlands but for the serious cycling tourer who wants to cover 100 miles in a day stick to the mellow back roads. A mountain bike would be more suitable for the NCN in the Scottish Highlands.