Moose are the easiest animal for a human to imitate, and still people want to use electronic gadgets. Kinda sad. How about learning some skills? Listen to some recordings of calling moose, and do it yourself. It is not difficult to learn and is much more versatile than pre-recorded calls. And more satisfying when you call one in.
Quite capable of doing both. The e-caller is just convenience - the modern equivalent of the apple juice can and the wet shoestring, rolled birch bark, your own hands, etc. Just as the telescopic sight and GPS are modern equivalents of the iron sights and paper map/compass (and a host of other comparisons). If the old method of calling is just as good, in terms of effectiveness and functionality, as the e-caller, there certainly aren't any 'fair chase' issues.