I'm sure you'll get a reply from Guy Fawcett, who is the guy trying to
drum up interest in a 1/6 WWI contest, and who has already flown a large
electric-powered Fokker DVIII.
I've been dabbling with electrics for at least 3 years, and have seen a
large number of electric scale models flown, but most of these have been
post-WWI types. However, I have seen a handful of WWI craft airborne.
The main advantages of this form of power are ease of starting, absence of
vibration, and no oily gunk spewed all over your model. The downsize
involves such things as forcing the modeler to build a very light, but
strong model, since you have to lift 2-3 lbs of batteries, and being
satisfied with flights of only 4-6 minutes, depending on the gyrations you
wish the model to perform.
The largest electric fly-in occurs each Sept at Hatfield PA (it's called
the KRC electric fly) and if you could find the time to attend, you'd
learn more about electrics in that weekend than at any other time.
I'd also suggest that you contact Ace R/c and obtain a copy of Keith
Shaw's video called "Power for Performance Electric Flight" which runs for
about 2 hours and gives all sorts of hints and tips from one of the
acknowledged experts.
If this piques your interest, I have several other sources of info for you.
Frank