I also suspect you saw a King Kombat. They fly great! The only SPAD I've ever seen come close to keeping up with a King Kombat would possibly be a Sickle. But after a mid-air, a Sickle pilot will probably keep on flying while the King Kombat pilot is walking to the crash site.

Here's my DaWing, which was evolved from the all balsa King Kombat. Does this look similar to the plane you saw?
http://mypage.yhti.net/~dmcdnld/dawing.htm