I am not a long time Trek expert, but I've had several '79 - '82 Treks in the past few years. All are 24", which is slightly on the small side for me, but I felt like they rode bigger.
The first two were a 500 and a 600 series that was probably sold as a 614 but the serial number is ambiguous. I liked the 500 better. The 614 is a decent bike, but to me it basically feels like many other solid, not particularly light mid-range bikes with 531 triangles. Definitely nothing special.
Within the last year I bought a 710 and liked it so much I bought another one three weeks ago. They are light and flexy, so I wouldn't necessarily want to ride one down a steep incline with 60 pound pack, but lightly loaded they are a joy to ride. Completely different bike than the 500 or 600.
Haven't tried a Columbus model yet.