I've finished all five now, and will marshall my thoughts and post some thoughts over the weekend, probably after I've finished the last Sarah Caudwell, which I also picked up in Seattle. I thought each book was better than its predecessor, actually, though only in Full Frontal Murder did I work out whodunnit before Marian Larch did - quite a bit before, in fact.
In the Mystery Bookshop, by the way, Barbara, were two odd-looking vols labelled "uncorrected proof copy, not for sale under any circumstances". They cost somewhat more than the copies I bought.
As for the opera mysteries, I was thinking of trying for second-hand copies online.