Experience of using the latest Freeview Pace digital set top box with twin features and a hard disc!
Downside to recording to the hard disc does not, and I repeat does not record the subtitles when you know they are on! This occurs either in touch record or when set to record in the timer mode!

Despite subtitles being on the TV at the time!
Upside is it will record the subtitles to VHS recorder, so far so good! Downside is you need to leave the Pace set box on all the time and set the VHS to record when you want it! so limited to channel selected!
So can DVD recorders record subtitles only manufacturers can inform us if this so. But to my knowledge no one I have spoken to in shops can attest to the possibility of this being feasible. Especially my local Panasonic outlet, home to the last VHS 888 recorder.
Unless. ... .... . .