You can get the unmic'd guitar cab sound from an FRFR if you use far-field IRs.You can never get the former (unmic'd guitar speaker sound) from an FRFR with cab/mic modeling. However, you can get more of the later (speaker sound bouncing around the room) with an open back cab.
And using an open-back cab with near-field IRs doesn't make for "speaker sound bouncing around the room." More accurate would be "mic'd speaker sound bouncing around the room." Whether that makes for a more amp-in-room sound is up for subjective debate I guess.