Thanks all, especially Leo & Wm for the info and useful links, that then led me to further info.

From all of this, I got the impression that they should do the job, if they don't get shocked.

However, after flying the plane for the first time today [with a single servo in place], I came back with such a big grin on my face that I don't think I need to bother. The thing lands like a hummingbird in half a strip length!

If I do get around to putting them in, I'll post the results at some future time.

Cheers.
Steve