Wow, lots of good info about Shenzhen Airlines.
Space actually opened up last minute on one leg SZX-PEK on Air China's 777-200 F so I grabbed that... the international config layflat seating won me over.
Sounds like Shenzhen Airlines is a good domestic China choice. I'll have to keep them in mind for future bookings since I travel to the Shenzhen area quite a bit and SZX is much more convenient than HKG/CAN.
Hopefully the F cabin 737-900 Shenzhen uses for SZX-PEK frequently is configured like their 737-800 with 48" pitch rather than the tight 38" pitch on their A319 aircraft though.