Is it safe to assume that scart will do the job?
I think you will find that HD is only available over HDMI and not over analogue such as scart, composite and component connections (due to DRM restrictions.)
The box might internally downscale HD to SD over an analogue scart connection though? However HD content can be recorded to the hard drive and played back later over HDMI to a suitable HD TV.
The older HD Humax freesat boxes did have a HD analogue out over the component connections and hence were not affected by DRM but that was unfortunately disabled some time ago.
BBC iPlayer HD 720p content can be downloaded using Linux and those AVC .mp4 files have no DRM restrictions and so can be played back over an analogue connection to a TV, burnt to a DVD, etc. etc.