There are gliders everywhere at this time of year and believe me, these pilots are very highly experienced and look out as well as anyone else does.
With all due respect to power pilots, I would say rather better lookout. Firstly, glider pilots all-round view is substantially better, secondly they receive a lot of soaring information from lookout .
No glider pilot I know would regard 1 mile separation as any kind of conflict, or dream of reporting it as an AIRPROX.
(The C152 who flew straight through my thermal near Newbury last year without any deviation from straight and level, and would have collided if I hadn't taken avoiding action is another matter. I took his reg and called his Flying School. Never heard anything else - i really should have filed that one through the system).