If in fact the scum are almost at parity with the town here (as some scenarios have suggested), then massclaiming really decreases our chances of making a comeback. It could not only out a remaining turk-cop, but also any other important roles (vig, doc, etc.) that will be almost necessary for winning. I think massclaim now could just give the scum too much info in return for very little.
And if there are only ~4 scum or so, then massclaiming probably won't help much either because, as IAAUN suggested, they might have strong party claims for starting off with fewer numbers. So far though, the two lynched scum (CML, Lowell), have had bland safeclaims (especially for SK; if anyone would get a better safeclaim, I would have thought SKs would).
In short, I think massclaiming now will out protown power roles and hand the game to the scum.
I also find IAAUN and Yos2's support for massclaiming here to be out of place. Yos2's reasoning is that it would "make it harder for them [scum] to hide," but I don't know why he thinks this is true.
IAAUN's reason is that it would allow us to semi-confirm Zakeri as town (not fully, because of scum-cop theory) or as scum. He also gives some setup speculation about safeclaims in 3 vs. 4 man scum teams, and even says that massclaiming could produce results that are inconclusive (if in fact a Turk cop claims), yet he still supports massclaim. The logic in 1670 just seems... forced.
I'm going to
And