Used to walk around it a fair bit when I lived down that way and often saw char topping up the far end on a summers evening. Would have been great fun on a light fly rod.
I believe the char often come to deeply fished flies, often as they come up on a vertical retrieve. A mate who used to fish it a lot before moving away had some big bags of fish (before these more enlightened days) and he would pass some to me for dead baits for the pike. They are awful bonny fish!
I concur with the wind issue. I have been blown off my feet several times in that glen, it can be very scary!
Small point of interest, the glen holds some of the oldest remains of human civilization in Britain, with cultivation and village remains evident.