I rode this road in summer 2008, from Lanark to Melrose. There were signs warning of biking accidents. I think that is because there are some trucks and buses, the road is narrow but fast, and the visibility is poor.
Its a good road, but take it easy.
I've seen the Police use this road a few times for their own driver training. Just look out for 4 guys in white shirts, the cars usually have a small "POLICE" sticker on the rear.
Good piece of road, can be joined together with several others in the area to make a great day's riding
I was "guest" above when I submitted that review - I have since had no reasons to change my mind! Although it does seem to be getting a little more popular these days, as my latest run showed.
What about the A708, Selkirk to Moffat, just off the bottom of your map? Far, far nicer road, with miles better scenery, tons of great corners, bridges with kickers, flik-flaks, open sweepers into and out of BIG straights with lots of attitude. The last few miles into Moffat are tedious but then you want to wind down for a fantastic lunch/supper whatever. I do it as a cicuit from North Yorkshire in a day!
A good combination of some nice bends and straights with fairly good visibility and the added bonus of a very limited police presence in my experience.