I had a few made (custom version) with all five rows of magnets (like the standard version) and the felt (like the pdr version) on the front side only. It brought the sensitivity up over the standard version and worked out really well in the open baffle.
The only hitch was that the back side of the mounting hole had to be shaped a certain way to make the rear output smooth like the front.
Oh yeah, one other hitch is that I have to order a bunch of them to get them made.