Rossw, magnetising current is magnetising current... no ,matter how you drive the core, the result will be the same if the primaries are the same and are to be parallel for high power... no difference.
If they are tapped for the primary, then you could use the tap with the most turns to get the amps down and the turns up for the same magnetising effect...... but then you have other problems with the head room.... seems more trouble than it is worth really.
Only by using smaller cores for the small power, and larger cores for larger power can you get any real relief.
I think Schnieder do this with three transformers of differing size from what Chris Olson was saying when he got them... but they are EI types so their efficiency is poor anyway you do it. Also their weight is not much different to mine.... and their transformer would have to be twice the weight of mine to compete with the torroid.... so they are under powered anyway compared to a torroid of similar weight.
The little one I am running at the moment has less than 30 watts idle, and can pull 9kw starts... thats fine by me... with more turns to both the primary and secondary, that can come down further too.
Or, put another way.......
If you have to worry about 30 watts, then you have more problems than just the idle current, and thats the least of the problems to be faced.
It is hard to get excited about .7 of a Kwh really...