That's a good point about the hours. We all work extra all the time, and I accept your point that this means that we are "owed" wages!
I think conceptualising strike action in academia is incredibly hard, because there is this vocational element to the job. A lot of people do their research because they love it, to the point that it's part of their identity. Traditionally, there's been a kind of balance between institutional pressures on admin, teaching and this personal element, that meant people were willing to accept lower financial remuneration (money capital) in exchange for the freedom to earn a kind of intellectual or cultural capital in their field - which then translates back in a host of still unequal ways, into promotion and higher earnings.
This balance has been increasingly eroded in recent times, in all kinds of ways that are too numerous to list here. The most obvious ones that occur to me are an increasingly managerial culture where admin hours are ever greater, an emphasis on grant income as a kind of off-set against wages (and larger student groups also), and the fact that papers are no longer the exclusive property of an individual, but part-owned by an institution post-Stern.
However, the persistence of a dwindling rump of vocational stuff in the job still makes strike action less than straightforward if it's about pay or terms and conditions. With this particular strike, though, the issue at stake is pensions - and (thinking aloud here) that seems to me to be slightly different in kind. Pensions are earned on the whole gamut of activities, from the most institutional to the most personal. So I can't see that a division between "personal" time and "institutional" time is that significant in this case, precisely because there is this circuit that feeds back from research excellence to higher earnings.
Here's the bit I'm less certain about. The lengthy nature of this action means that I don't think it will be possible for people who don't want to participate to work from home for a day or two and rearrange teaching quietly. Over 14 days, it's going to be more obvious than in previous cases whether someone is present or absent, and I imagine HoDs are going to be under a lot of pressure to report teaching that hasn't been done after the event - not least because students will kick. I think this means that disruptions to teaching will tend to be captured and measured in a different way to previous, shorter strikes, which means that those who are striking but still asking to be paid are likely to get "caught". (Morally, it also strikes me as simply unfair of people to ask managers to lie about this because they want to strike but also still want to get paid! People need to take personal responsibility for this decision).
To be clear: I think this situation is unfair, given all of the overtime we all bloody work all the time, for free! SATURDAY OPEN DAYS FOR INSTANCE! I accept the moral case about the hours. But I think universities are more disciplinary institutions now than they used to be, and I fear that students will not, in fact, feel much solidarity.
Finally, I wonder if non-reporting will be a tactical problem for the union. I don't know how universities could really measure participation in a strike (and thus strength of feeling on the issue) apart from noting how many people were foregoing pay?