I had a great day out in the Cairngorms recently, riding from Inveruglas to Glen Feshie, and up to the summit of Braeriach. I put a video on YouTube. Don't expect any amazing bike handling, but if you're thinking of a ride/walk up that way you might find it useful in terms of the type of terrain etc. The scenery & cloudscapes were pretty epic!
Are there two different Inveruglas? The one I know is by Loch Lomond, so it sounded like a monster ride!
I've been thinking the same, was about to go and open MemoryMap, then do a Ctrl-F!
Edit - yes there is, it's a farm just south of Insh Marshes (actually "Inveruglass"); that makes much more sense than the one west of Loch Lomond.
Looks like a cracking day out regardless of the spelling; good work all round