I just wanted to update my posting, although I think all the great info here on drives, compatibility and what works/doesn't, etc, has been more valuable than my initial question. FWIW, I have since solved my problem, but without changing drives or styles. I had never updated my operating system on my HD24. I had to go through the process of acquiring the proper integration software and learning to connect my Mac, etc. But after several tries I still couldn't seem to make it happen, even after I believed I'd done the procedure correctly, and even after I swear the HD stated it had the latest operating system installed. At that point, the Alesis moderators suggested that the update could only be done via MIDI, and since that opens up a whole different can of worms for me, I got sidetracked for a few months. Later, I retried the same update via ethernet connection, and VOILA ... I almost couldn't believe it. But now y'all can appreciate why I haven't gone to a DAW ... just get to lost in all those menus, updates proceedures and protocols. The analog world is so much easier for me to integrate, and the HD represents a digital tracking solution that feels (mostly) analog.
Thanks to all who contributed
dd