I am an instructor floppyjock. And when flying in that area I was always talking to scottish info or leuchars when IFR. And that wasn't just in SEP's it was in twin TP's as well.
And as for commercial crews they won't carry VFR charts although we used to because our ops manual allowed us to cancel IFR. They may only get there briefing pack 10 mins before departure, that pack may include FIR Notams. But always departure, TO alt, destination and alts aerodrome NOTAMS. They will not phone that list of yours. If they don't have local knowledge they won't even know there is a drop site until they get the Dundee plates out if it is mentioned on them. When they will find out depends on what they do if they go the long way round and drop out of P600 it will be mins before arrival if they take the longer transit through class G but shorter track miles its when leuchars gets them.
Folk heading North from England have several choice points depending what the WX is doing cross west/east before Leeds or continue up and do it over fife. Setting off from Turweston I would have a rough idea which way I was going but I would be 100% certain that it would not be anywhere near any line drawn on the chart.
And its not exaggeration, if things have improved thats good. But as I suspect there will be a re-assement of the risk assement (if there is even one) after the airprox report is out we shoud proberly leave it.
And its hardly 365 days a year is it.
Its at the most 100 days, proberly less planned. And less than that actually flown.
And you still haven't answered the question if other users are still using the site and the DZ protection when your not jumping.