I've always wondered about the interest in (and sometimes confusion about) the EP-5.
Occasionally someone will conflate a Little Joe (EP-4) with an EP-5.
Only two of the twelve Milwaukee Road Joe's were EP-4's, the rest were EF-4's...
Anyhow, it was Lionel/MPC that hung the name "Little Joe" on the EP-5 on the re-release of the locomotive in the 70's.
My theory as to the popularity of the EP-5:
1) Snappy graphics. The McGinnis paint scheme was a bold departure from the New Haven's Hunter Green and Gold. Even in Lionel and Gilbert Postwar catalogs, the EP-5 literally jumps off the page.
2) It's a compete thought. The EP-5 looks like two (almost Alco FA) locomotives back-to-back, giving the impression you've got more locomotives pulling a train than you actually do.
3) It's just plain cool.
Well, Great Northern and Milwaukee Road both had significant electrification, and frankly the EP-5 looks good in those paint jobs. It's not the first time a company has stretched the truth. MTH, K-Line and Williams both offered their O gauge EP-5's in non-prototypical roadnames. In contrast, back in the late 50's Penn Line offered their HO GG1's in New Haven and Great Northern.
Personally, I'd like to see the Flyer EP-5 offered painted up in Chicago, South Shore and South Bend.