I think they are the m40fs headphone (sound-wise, based on my memory). The street price for the 45's seem slightly higher, but I don't know if they are "better". Musician's Friend and Guitar Center aren't carrying the 40fs anymore (at the moment), so maybe they are being phased out (? you can still get them other places, though).

I think if you like the 40fs, you would like the 45's.

Now at bandcamp: Crows Say Vee-Eh @ bandcamp or soundcloud: Kevin @ soundcloud