My Beni Shichihenges have always been well behaved.With variegates,if it's just an odd leaf here&there I leave alone,and see if it re-occurs next year.I only remove if more non-conforming leaves grow from that point on the plant.

Thx - it is just an odd leaf here and there, mostly larger than the variegated ones, and I will watch to see if it does it repeatedly in the same spot. None of my other variegated maples do this.

One other question - my 'Ukigumo' seems to alternate years of much lighter color. One year the variegation is mostly white, the next mostly green. Am I imagining things? I have read that the variegation on this one increases significantly with age, and this is a fairly young specimen (about 5' tall).
Thanks!

Yes,this one is a bit finnicky,more shade for best whiteness,the better it grows,the less the variegation sadly..I found by just moving it about 1ft,to give it just 1hr more sun,it came out green.I think maybe a sunnier year could produce the same effect,though more fertiliser would also cause this.I've moved mine back into more shade,hopefully it'll come out white again this year.As you say,the bigger it gets,the less effect changes in light and growing conditions will have......I HOPE!

Mine is in dappled shade - I, too, could move it slightly to get it into more shade, although it is now big enough so that I would not do it lightly. I'll watch sun patterns this spring/summer. I pruned the canopy over it (Cercis chinensis - mature specimens) last year, which may have allowed a bit more light in - that may be the culprit and I didn't think of it until you mentioned the subtle differences in light affecting the variegation to that degree. Always something to learn...
Saw on your profile that you recommend BS as a good one to start with. This, for no particular reason other than serendipity, was one of my first!

Here is a link that might be useful: Form and Foliage

Ah the reduced shade could explain the change.Your tree is getting quite big now,so may be able to handle the extra light without reverting(Ukigomo is renouned for reverting if growing too well)If your Cercis is going to shade it again later it may be ok to leave the maple where it is.It's a case of what you're willing to put up with,though if it starts putting out a lot of large plain green leaves I'd move it.I bought Ukigomo for it's white leaves,when present it is my favourite maple full stop.For this reason I'm gonna err on the shadier side in future,even though it won't grow fast,the white leaves are the most important feature to me.
Well some people in hotter climates haven't been so lucky with Beni Shichihenge.It was also one of my 1st maples.I put it straight in the sunniest spot in the garden(english sun?!)as a young plant,and it has never flinched,lost a leaf or reverted...just sits there happily in full sun all day...quite amazing for a variegate.The colour improves every year and it exactly mirrors the colours of a japanese willow planted nearby ha.
Good luck with your trees,they're both lovely cultivars.