Is it the use of technology you guys are objecting to or the thought that someone else might know where you are?
Neither. Probably 70% of cross country gliders carry Flarm, and almost all of those are trackable on OGN (which has a feed to FR24, which is why you can see them there). So neither technology or being seen are an issue.
The issue is effectiveness, and a lack of evidence that radio and transponder are particularly useful in preventing mid airs. Sure, they have their uses - I carry and use both in my glider, and this thread is built on a BGA letter encouraging glider pilots to call certain ATC units on the radio, and I support that.
But.
A radio gives slightly improved traffic awareness, assuming everyone is on the same frequency. They aren't in class G, and anyway the information is generally too imprecise.
Whilst my having a transponder helps ATC keep the heavy and fast stuff away from me, it does very little to help me avoid the average GA pilot, unless at least one of us is in receipt of at least a traffic service. As discussed earlier, a basic service doesn't do it. And traffic service isn't available when it gets busy.
For gliders, the risk is glider-glider collision. This is at least an order of magnitude more likely than hitting anything else. For that, the technology of choice is Flarm (after looking out the window). A major benefit of Flarm is that it actually gives information about traffic to the pilot that's carrying it. Now, there are other technologies that do that (eg TCAS, ADSB), but for cost and regulatory reasons they aren't extensively carried in the GA community. (The equivalent risk to powered GA is other powered GA by the way).
And lastly cost. If you're flying an aircraft that costs, say, £10K, then spending £2K on a transponder that has very limited value to you doesn't seem sensible. Especially if you have to spend more to upgrade the electrical system to support it. And there are lots of gliders, microlights and others in that category. So the cost / benefit is limited - a glider pilot in particular would be much better spending the money on a Flarm (1/3 the price and no regulatory issues), and even then it's hard to make a cost / benefit justification in the UK.
It seems to me that if you want to achieve adoption of a technology, it has to give a benefit to the person paying for it. One day, perhaps the fabled low cost ADSB will be here (and if the developers have any sense it will be Flarm capable as well), and we can get good traffic information on the panel of GA a/c - powered, gliders and all (BTW, that also implies displays that can show that information, in a way that doesn't encourage more head down time - there's always an unintended consequence!). But it seems to be taking a long time.
(BTW, I have roughly the same number of gliding and powered hours, many of the latter IFR, so I'm not coming at this from one side of the argument).
Paul