The original costume is quite lighter than we remember for some reason, I'd say you're pretty well ball-parked. The other colors absolutely will affect it's perception, the classic optical illusion contrast effect, and yeah, expect any weathering washes to knock everything down a shade or so too. If you'd like to change it to something you more like though, I'd say go ahead, the variable appearance of the original color offers a sorta wide window to get a color you personally think is more 'right'. I've seen a lot of really amazing paint ups which are a way-off dark green, but still look very ESB iconic.
