Hi,
I have been with this tiny board for 2+ years now running FreeBSD 6.0 thru 7.0, and recently moved to 1.2.1/1.3 when pfsense incorporated newer kernel 6.3/7.0 respectively.
Yes, the Marvell chips were a kind of headache while using FreeBSD but it's now supported officially and works just fine with the msk driver, however, I would recommend using the myk driver from Marvell themselves because it is much more stable than the one in the current kernel. You can of course need to rebuild and configure the pfsense kernel which won't load its default msk driver but myk driver. That's what I do now.
One last note, if you decided to go with kernel's msk driver, don't forget to add the following line in your /boot/loader.conf;
hw.msk.msi_disable="1"
otherwise your Marvell will easily screwed up with the messages below even in light/moderate traffic…
msk0: watchdog timeout
msk0: link state changed to DOWN
msk0: link state changed to UP
msk0: watchdog timeout (missed Tx interrupts) -- recovering
Hope this helps.