I have been using the Alpha Stim for about 4 months now. I do not experience a "high" or feel compelled to use the unit. My experience has been that it has been a much more subtle change in my thinking pattern. As my anxiety has reduced, I have experienced changes in my eating patterns. I am not as likely to go for "comfort" foods (generally high calorie high carb) to deal with stress. I am relating your question to mean something similar to a "runners high" - where runners or other athletes are compelled to run, to seek out the high feeling they get from running.
In my experience I don't feel a compelling urge to use the Alpha Stim, but I realize the benefits I have gotten from it and want to continue using it. Others may get a different reaction. As far as I can tell there would be no harm even if someone became "addicted" to using the Alpha Stim, as it seems pretty harmless.
Alpha Stim and ECT are so extremely different, there is no way to compare them.