JP:
All the maggies are worth checking out. I haven't tried them all, but so far the 260 is my favorite. It's the sound ... a unique clean tone, beautiful OD higher up. Excellent bass presence, at least with the CRexes I have in there. Way more volume than the the stock Oxfords. The 280 is quite different, not just because of the stereo setup. Uses different tubes I believe. Came stock with heavier duty Oxford speakers, still could use an upgrade. Stereo is sweet, but I prefer the 260 sound.
The suitcase models are out there, even for magnatone. I've played several, own an M10A. 12" speaker, 2 x 7189A (higher voltage, more rugged EL 84 type), two channels, one with vibe, great reverb, lots of interesting tone shaping options -- such as top boost on either or both channels, "stereo" switch for running through both channels (in mono actually). Think 18 watter from outer space. Not a typical EL84 sound at all. The tubes are different, hotter. Plus, the cab construction and layout (with a folded horn of some sort in there with the speaker) are unlike anything else, essentially a closed back cab. Once again, great amp as is, even better with a more efficient speaker. The vibe on the M10A is not much like the 260 effect. On the M10A, more chorusy sounding. Love this amp! It's not remotely like anything else, a great swampy screamer that gets some mighty strange looks until you plug in. Then everybody has questions ...