I don't have much experience with the HD24 - however, I am currently using 2 RADARs with my tandem DA7 setup. The RADAR is, in my opinion, arguably the best sounding digital recorder made today - quite a few of the engineers & mixers I work with utilize the RADAR's converters as the front end to their Nuendo & Pro Tools rigs. The build is pro and user support from the manufacturer is impeccable.
Some RADAR users do complain about it's unique editing scheme, that it takes some getting used to. Also, if you are used to Pro Tools, Performer, etc., the waveform display is a bit archaic, not as flexible.
In my opinion, sound counts - try, if you can, to compare the RADAR with the HD24 side by side. I have done a fairly non-scientific comparison between RADAR & Pro Tools, Nuendo & Performer (with their proprietary hardware). I liked the sound of RADAR best.