I might have considered it in the earlier period actually, or even the wild-challenged trials, except that I was forming a support-bubble with someone (not long out of hospital for an injury, mere weeks before the whole thing blew up) which meant I wasn't really at liberty to put myself in either situation. Still am, in fact, but more for sanity reasons than physiological ones.
(Also, I was nowhere near the Oxford/wherever trial catchments, so my application would never have been seriously taken up.)
With a clearly low case-mortality (even for my age) but high R0, you end up with a higher population mortality than a high CM/low R disease. I'd have prefered (would still prefer) guaranteed monitoring with guaranteed immediate exposure over what is almost guaranteed future exposure if we are still wishy-washy with facts and treatments for too long.
I have never had a test (nor my support-bubbler, and neither having sufficient cause to book one) and for all I know we've both been silent-but-deadly after one random public exposure in a supermarket trip/whatever and thenceforth put others at risk in future supermarket queues. I'd have much better peace of mind if I'd been in a Phase III situation (or pre-screened and rejected), and only have to worry about silent reinfection chances than whether or not I'm still truly unexposed. (I suspect it's also this sort of thing, but far more misguidedly applied, that drives the Covid Party types - with either known or unknown potential 'givers' present - but I'm unsocial enough to not have any need to let my hair (and guard) down in that sort of ad hoc manner.)