I have a single-band (10-meter) Sirio SD-27 rotatable dipole that I like. I picked it up at a hamfest. It can be oriented as a horizontal dipole or a vertical dipole. It is light enough that a TV rotor can easily manipulate it.
I have no experience with the MFJ-1775 rotatable dipole, but looking at the manual, I note that the bandwidth where the SWR is less that 2:1 is only 60kHz on 20-meters, and only 40Khz on 40-meters, so only a small slice of those bands will be workable.
I also see Diamond Antenna HFV-5 HF has a multiband rotatable dipole. I might expect all the multiband dipoles probably have narrow bandwidth.
Good luck & 73,
-Mike W1TKO