I've got the Mackie HDR2496 and like it. I don't have any experience with the others, but I lust after a RADAR for some reason :D .

Pros for Mackie HDR:
- Sounds fine (analog I/O AIO-8 Cards)
- Stable (for me anyhow it's been rock solid)
- Great editing
- Easy integration with other studios using BWF file capabilities.
- Now capable of simultaneous Analog/digital I/O
- Company hosted User group with knowledgable user base and "official" representation.
- 2 remotes available depending on your needs/budget

Cons:
- 32G max drive size
- IMO they've made the file management more complex as a result of moving from project/multiple playlists to Folder/multiple projects. The gui doesn't feel like it matches the new conceptual model. I think I've seen reports that purging unused files in one project may cause deletion of audio files used within another project in the same folder.

This is a good machine and a good match for the way I work.

I had the Mackie MDR and sold it for the Alesis HD24. I think sound quality they are comparible maybe a slight edge to the HD24 as far as converters go but not drastically. The reason I switched was the ability to use off the shelf hard drives instead of only expensive Mackie ones. If you record a lot, the Alesis could be a big saving to you in the long run.

I recorded a 24 Tracks project last month with a Mackie HDR2496, and I've been involved in recordings with Tascam MX2424 several times; here's my opinions about those two: the Tascam is better sounding, with clear and transparent converters, has a lot of compatibility with Pro Tools studios (via SD II and BWF files), but my problem with it was with the user interface which was not so friendly and intuitive, plus, the software version, being one of the first to come out, had a few bugs that got me into trouble with the recording process (like automatic punch ins and outs at the machine discretion...), but I think by now these should've been fixed. In all it's pricey, but a really pro machine, only you have to spend a little time in getting around it.

The Mackie is a little more straightforward regarding ease of use (if you hook up a keyboard/mouse and video is really a breeze to use even at first time), and the sound quality isn't bad even with the standard cards (the one I used had Apogees in); the only issue I encountered (apart for the 20 Gb max size of the drives, issue that should be fixed with a SW update), is that when the machine was maxed out at 24 trk recording I experienced some digital drops on all of 24 tracks, and I've yet to determine the cause (but I suspect a poor drive performance), luckily I can fix those by editing with prerecorded material from rehearsals).

If you don't need the editing features of the HDR go check out the MDR or SDR also from Mackie which offer the same recording features minus the editing at a really rock bottom price (I'm considering an SDR2496 for my remote recording gigs).

It seems that the Radar sounds soo good that I'll have to check it out.

In the end I think either way you get a really good HD recorder for a reasonable amount of money (and in the SDR case a real bargain).

Hope this helps