Still looking at this route. There are logistical problems in particular this year. Getting to the start at Glenbrittle hostel – there is a bus as far as Drynoch or the Sligachan but (assuming you don't have a chauffer to drop you off at the start) – but you would then have to walk to the start – about 7/8 miles from Drynoch – or maybe get a taxi from Broadford. No great issue. The main problem is that the Glen Elg Skye ferry is not planning to operate this season – it is Easter to October usually. https://skyeferry.co.uk/
You could start in Glen Elg which would still give a magnificent walk. There is a bus as far as Shiel Bridge but would then have to walk or get a lift over the Mam Ratagan. When I did the TGO challenge 2 years ago and started at Glen Elg I stayed in a lovely B and B owned by a Gaelic speaking lady, Maggie Cameron. She offered me a lift from the bus which I declined saying I would walk. Got to the top of the pass and it started to sleet heavily – Scotland in the spring. A car drew up and it was Maggie who had seen the storm coming and thought I would welcome a lift – I could hardly say no.
One very minor diversion you should definitely consider between Bridge of Orchy and Loch Lyon is to visit Tigh nam Bodach at NN381 427. I have never been there and it is top of my list of must go to places.
“The ancient pagan shrine of Tigh nam Bodach is located in Glen Cailliche (the Crooked Glen of the Stones), north of Loch Lyon. The shrine is made up of a modest stone structure that houses a family of three bell shaped water stones from the river bed of the Lyon. The largest represents the Cailleach (old woman), accompanied by the Bodach (old man) and their daughter, Nighean. In what is believed to be the oldest uninterrupted pre-Christian ritual in Britain, the water-worn figures from the River Lyon are taken out of their house every May and faced down the glen, and returned every November.�
Magical in every sense

Mark I am very glad you posted about this route – one I had never come across before although it visits areas I know fairly well. I downloaded the route from the LDWA Long Distance Walks page onto Memory map and have wasted part of a very wet and dull afternoon looking through it.
It looks a fabulous route passing through some very remote and lonely country. Obviously it does not cross the high mountains because it is based on the old drovers routes but it would be easy to adapt it in places to go high. For example from Bridge of Orchy to Loch Lyon you could head up to Coire an Dothaidh and follow the ridge line rather than traversing the lower slopes. From Pubil, Loch Lyon you could follow the track South to follow the ridge line over Meall Ghaordaidh and Beinn na Oigreag.
You ask about the amount of road walking. Clearly there are a few long stretches on roads – but this is far outweighed by the cross country sections and you will find that most of the road sections are not as we know them further South – they are pretty quiet and very scenic. I suspect that if you measure up the road sections as a percentage of the route it would be far less than on many other long distance paths. There are certainly places where the route shows it to be on the road where there is a good off road alternative.
For example if you wanted to avoid the road section along Loch Cuaich (which despite being road is a good walk) you can go North to Altbeithe, head East to the river Loyne and cross the Mam na Seilg (a fantastic viewpoint) to rejoin the road.
From Achnacarry to Spean bridge there is a path – now part of the Great Glen Way – that avoids the road to go along the shores of Loch Lochy and from Gairlochy to Spean Bridge there is a relatively new and very attractive path along the old railway line past Wade's High Bridge. From Comrie Town Centre there is a path (The Bogton Braes Walk) that follows the South bank of the River Earn to near Drummonderroch – you could then head East on the road a short way before crossing the river at Trowan and picking up a path on the North side of the river (The Trowan path) which takes you to the site of the Crieff Tryst (where the cattle were bought and sold) before reaching Crieff town centre.
I think you may find you have company when you start the walk – it has made me reach for the tent and sleeping bag.

I suspect from the lack of response here that there won't be many people who have done this walk.
I've had a look at our GPX file and, although we describe the walk as moorland, there does appear to be several stretches which follow roads and some of these are quite lengthy.
Although we show the associated guidebook as no longer available, from a quick internet search there does appear to be some available for around £10.
If you are a member of the LDWA Facebook Group, it might be worth asking your question there.
Good luck if you do undertake the walk.

Hello friends

I am considering walking the Famous Highland Drove Walk. I was wondering if there is a lot of tarmac/hard surface walking in this route.
Any other tips, advice and experiences also much appreciated.

Thank you
Mark