Don't really know how fast our planes really go. We had a guy come out to our field once with a radar gun and clock some planes. An average speed for the sport planes flying that day was 75mph. The fastest plane he clocked that day was Great Planes(?) Tamecat (wanttabe Tomcat) @128mph.
Scale warbirds come in all sizes, generaly scale warbirds have high wing loading thus the tendancy to build bigger ones. When you get into bigger models then the tendancy leans to gas engines, a lot of that is economics, my Q42 runs 15-20min on 16oz of gasoline/oil mix@$2.10gal, my Super Tiger 2000 runs 8 min on 16oz of glow fuel@$15gal.