In past years at our annual workshop, we attracted a heavy number of traditionalists attached to the 1962 Missal -- and this was long before the Motu Proprio. They attended various indult parishes and some SSPX parishes too. Of course they can't have been too strict because they were attending an Ordinary Form parish workshop and participating in an OF Mass - and a vigil too. So they should be given credit for being willing to do so; certainly in those days, the Extraordinary Form people tended to be rather tough minded, so this was something of a stretch for them.
But if their true loyalties were unclear before the liturgy, it became very clear during the part of the Mass when everyone shakes hands: the famed (and often dreaded) "Sign of Peace." The OF Catholics would reach out their hands to the EF Catholics, who would often just look back in alarm, as if to say: hey, I don't do that sort of thing! I always found this sort of amusing. (I'm not making light of the seriousness of the subject but I do find it interesting how revealing this behavior can be.)
Well, I was a bit unclear about the demographic of this year's workshop, but I only needed to wait for the sign of peace. Nearly all the workshoppers gave the sign of peace with warmth and ease -- pleased to do so. I don't think anyone recoiled. This confirmed for me something very interesting. Nearly all, if not 100%, of the attendees were OF Catholics of one sort or another.
In some ways, this pleases me very much to see sacred music now making such inroads into the OF - and note that this comes about following the Motu Proprio that liberalized the EF. We've all speculated for some time that the MP would actually have the effect of liberalizing tradition within the OF structure -- and this was confirmation for me that this really is happening. There was a time, not too long ago, when anyone who favored chant and polyphony was pegged as a traddy. No more. Certainly times are changing.