And it looks like even when booking a reward night you must now cancel 3 days in advance...

Not aware of any other IHG properties where this is the case (not to say there aren't' anyway, but I've never come across them).

Also, with the none refundable rates being bookable until 3 days before arrival, one might as well cancel the flexible rate and book the none refundable one 3 days out, because that's when all their rates become none refundable anyway...