@hartf36: Yes indeed! Now you may want to check out the OB/Dipole Sub offered in collaboration between Brian Ding of Rythmik Audio and Danny Richie of GR Research (as is your F12G). It uses two or three (your choice) of the same paper cone woofer as found in your F12G, but the driver electrically optimized for open baffle use. The woofers are mounted in an open baffle "frame", the sub therefore propagating sound in the same manner as dipole loudpspeakers---from both the front and rear of the drivers. The ultimate sub for Magnepans (as well as all other dipoles)!
A dipole woofer system has been under development at Magnepan for the past few years, and will eventually be offered in both the upcoming "30.7 For Condos" model and as a stand-alone sub for use with the company’s other models (as well as those of all other companies). It is not, however, an open baffle design, merely a dipole. Numerous woofers mounted in a sealed enclosure, drivers firing forward and backward. Can’t wait to hear it!