Neither does Samsung

Check your facts before making owners of A and C panels worry.
For the reocrd Samsung does not make a 2ms panel either. The panel in the S screen is a 5 ms panel with Samungs patented overdrive technology increasing the effective speed to 2 ms. Not beyond beleif that Samsung supplied this electronics to the A and C panel manufacturers to make their screen 2ms?
Yes, the manufacturers of the A and C panels do not list the panels as per the spec in the 226BW however from reviews and analysis they are clearly nearly the spec or identical to the Samsung panel therefore Samsung could have and obviously must have supplied components to AU Optronics and CO to enable them to make panels near to Samsungs spec.
Quote from Behardware:
"They look for the panel and find an "AU Optronics M220EW01" – which corresponds to an AUO 22 inch panel, however, a 5 ms. There are some who would take this very badly indeed. Luckily (!), we don’t have to go this far as the panel is indeed a 2 ms. Actually, it’s a 5 ms with an optimised overdrive. As a reminder, Samsung calls its overdrive, RTA, for Response Time Accelerator and only they can use it. This is why it’s strange to find the RTA function in a hidden menu of an AU Optronics screen, something they could not do without Samsung’s consent. This reinforces the hypothesis that Samsung simply delegated the manufacturing of some of its screens to AU Optronics and CMO, giving them precise instructions and even specific components. Either way, the RTA function found in the series A tends to suggest this. "
See Behardware for full details:
http://www.behardware.com/articles/667-6/samsung-226bw-a-and-s-series-the-verdict.html
Overall, the A and C panels can both be calibrated and setup to match the S panel. They are all 2ms rated monitors. The only question mark is the quality control is worse on the A panels and even more so on the C panels.
If you order one and you aren't happy with th quality, send it back. If you calibrate it and the backlight is no worse on your A or C panel than the S panel then keep it.