Just happened to notice this this and thought "what the hell".
In 2011, while perusing the new fiction shelf, I grabbed a couple of mysteries written by Ms. Heyer. When I took the books to my Mom (she loves to read but doesn't always want to go to the library) she exclaimed how much she'd loved reading Heyer's Regencies when she was younger and just married. I asked about the author, because my mom was married in 1955...and I didn't really think Ms. Heyer could still be alive. She wasn't. Anyway, the acquisitions dept for my library had pruchased the Heyer books as they'd recently been rereleased. Mom was thrilled as I was able to pick up most of her romances (save 3-4) and all of her mysteries. After hearing her wax rhapsodic about the books (most though not all) I decided to read some of them. At the time I was in a romance mood, and as I love Regencies, started there and ended up reading them all. Some of the books were too silly for words and I hated them, most were okay to good, and about 6 of them made it to my reread shelf. Those I absolutely loved. I'm unable to recall all of the titles, but BlueMtn you listed some of my absolute favorites: These Old Shades, Devil's Cub and The Grand Sophie were the absolute best.
On a side note: has anyone read the book Georgeete Heyer's Regency World by Jennifer Kloester? It's an interesting book that details and defines words, phrases and customs of the era. Ms. Kloester also included (very) brief biographies of some of the most well known and major players of the time. Oh, and according to Amazon she released a biography of Ms. Heyer herself in January, which I've not yet read.