Just in case there are still some of you out there contemplating the question of paint colours to use, I thought I'd share my recent experience.
I have one of the Athearn Hobby Craft units (#912), which I got back when they were first released, but I decided I wanted to expand my fleet. With the Hobby Craft units now virtually impossible to find (I wasn't interested in a $200 or more bidding war on eBay), I decided to try painting one myself. From advice from this forum and elsewhere, I decided to try using Testor's Chezoom Teal Pearl, and I'm quite pleased with the results.
I started with an Athearn Amtrak Ph 3 P42, and stripped the shell using nail polish remover pads (worked incredibly well, I highly recommend it! Just be careful with the fumes!). I then primed the shell with a white primer. From what I've read elsewhere, the undercoat used with Chezoom Teal is quite important, as it may change the shade the paint appears on the finished model. All advice I've found suggested white, to bring out the full colour (and not make it too dark!). After priming, I sprayed the entire shell with Chezoom Teal (I was using spray cans, but you could also use the bottled stuff in an airbrush....just be sure to be confident with whichever method you're using).
I then used Microscale decals, and finally sprayed the whole model with Dullcote, before adding the other details. The trucks, battery boxes, reservoirs, and handrails are all painted Testor's Flat Dark Ghost Gray (I believe). Here are some photos of the finished locomotive:
(for larger images, visit my Flickr page at http://www.flickr.com/photos/timberley512/
Depending on the lighting, the paint may appear more green than it does there. Either way, I think the paint colour is a good match for the original paint on the P42s. It is definitely not a good match for the bright blue that is on most of them at present, and is not green enough for the new colour on 917. Either way, it's good for what it is.
I should note; This was my first ever proper HO scale paint job, so if it's not quite perfect, that's why. Overall, I'm fairly pleased with the results. I am planning to paint at least one more P42 in the future, if not more. Once Rapido eventually brings along those LRC coaches, I need a good fleet of P42s to pull them!
Anyway, I hope that might help some of you debating on how to paint your P42s. I haven't yet decided if I will do more in this colour, or try a brighter blue on future models. I've also been trying to figure out how to add that third headlight....ideas anyone?