most of them can after rolling back the software and putting new software back on. a lot have people have done this with no problems. i have not as i have only region 2 discs.
HD-EP10, HD-E1 and the XE1 all have region free firmware for SD discs as well as an RCE hack for those Fox R1 discs.
The RF firmware is applied at 2.51 then you can upgrade to whatever the latest is without losing it.
I had an EP30 but got a cheap EP10 for that very reason.