The positive nature of discussion on this thread is very encouraging. this is not a subject for division into 'them and us' camps.
Backpacker - personally, I am not worried. Unless something hits my rotor or chops off my tail I am likely to survive a close miss or even a "bump". However, UK air law tells me to give way to gliders and I am very happy to do that; I can't unless I know they are there.
I always have radio contact when flying (local tower / radio, or LARS, or London / Scottish information). If the ATC unit knows / suspects from intermittent radar return that a glider is ahead of my track they tell me. I can change course early and deconflict with ease - mostly never actually ever seeing the glider. A x-country glider pilot in UK airspace talking to LARS is not going to get a lot of help from them (agreed), but occasional position reports from the glider gives everyone on channel information to plan to avoid; anyone later reporting a position that might conflict is advised of the risk by ATC and, again, sensible pilots will simply plan to avoid that particular piece of airspace.
Generally speaking, I am not after a traffic service to help me to fly close to gliders but I can't simply avoid any airspace where a glider "might" be; there is just not enough airspace in the UK to do that.
Similarly with transponder - if you show-up to ATC they tell me of potential conflict and I change course and avoid. I don't want to get close enough to need a FLARM warning.
I come back to what I think is my main point: If we continue to have complaints about near-miss, or actual accidents, that can be traced to lack of visibility then at some point official-dum will decide that 'something must be done' and we will have new rules (of some kind or other). It seems to me to far more sensible for us - the aviation community - to work this out ourselves. That way we may avoid expensive and / or ineffective measures being mandated.
So -
1) Is there a problem of visibility? simple yes / no
2) If so, then is that a risk that can (sensibly) be reduced? and
3) If so, what is the most cost-effective option?