The new legal size and padded FR envelopes go for the same price as the regular old FRE's, i.e. $4.75 online or $4.95 at the PO.
Over-stuffing FRE's has always been a no-no; you need to be able to close and seal the flap without cutting or modifying the envelope, and the same thing applies for the new ones. It appears that now that the rules have been clarified for most post offices, they'll start enforcing them better. The ridiculous claims by some shops of being able to ship vast quantities of fabric in a FRE will hopefully be modified, or if they're doing it, hopefully the PO will start rejecting them.
I just received the new padded and legal FRE's the other day, the padded ones will obviously hold less than the old ones, but will be useful in some situations.
It appears by the instructions written on the outsides of the new FRE's that the new ones may also be used for international shipments like the old one.