Well, keep in mind this is what I have read, not experienced --
- don't pay too much attention to the low freq. extension number. It's a guide, but doesn't say at what SPL (sound pressure level) this extention is measured at. At a higher SPL, the bass response is almost certainly peakier. The number isn't uselss but buying decisions shouldn't be entirely based on this number either.
- the larger driver on the PDR 12 gets more volume and extension, but it won't be a roomshaking difference.
Once again, IMO

save your cash for a bigger upgrade.