Hi Mike.
I rode this as part of a huge loop a few years ago. What I remember most about it was being utterly f***ed most of the way with a burning sensation in my thighs for mile after agonising mile. Don’t let that put you off though! It was in March and I think it was my first ride of the year.
The Strath Rusdale route is part of an old road, so it’s basically a mix of LRT and overgrown tarmac. All perfectly rideable in a beautiful, remote part of the country. I think it gets a bit rougher as you get towards Glen Calvie and there’s a lot more up and down, but it’s all good LRT as far as I can remember. I’m not sure how it would be on a touring bike cos I’ve never ridden one, but you’d want sturdy-ish tyres and strong arms to cope with the jarring.
Definitely worth a go.