Here is a conversation I had with a LARS unit a couple of years ago:
"Traffic 1 O'clock, 3 miles,opposite direction, a Bonanza at FL45 under my control, multiple targets 12 O'clock, 4 miles, no height information, could be gliders or ground clutter"
I was IFR in IMC with a RIS (obviously), and not near a gliding site. My rational was "ok, the Bonanza is under his control, so I will maintain altitude and heading and all will be ok. Could be gliders ahead, but I'm not near a gliding site on the chart, so it is probably spurious echos. Besides I am in IMC and likely that if it is gliders, they will be below the cloud base with is a good 1000' below"
It WAS gliders, as I passed over the "echos" the cloud was breaking and I could see them below me. Possibly had I known at the time that gliders could legally enter IMC then I may have thought a bit harder about the concequences. I didn't know that gliders could enter IMC, but a reasonable assumption, and it is clear that I am not the only one who didn't know ("clear of cloud and in sight of the ground" I seem to remember from air law).
I have no problem with gliders being allowed in IMC, from a qualification point of view (they can do what they like as far as I am concerned - though I don't think a glider pilot is any better at surviving the "Leans" than a powered pilot seeing as its a physiological thing you can't be "trained" out of), though I really don't want to run into anything at 120 Kts especially as I don't wear a parachute!
I appreciate the problem with 1000 gliders sqwarking, though couldn't they use one code, then ATC could have told me "Gliders 12 O'clock 4 miles, no height information" and I would have definitely altered course......
Cheers