Hi Rich,
Well don't look to me for inspiration on weathering... I built a mineral wagon, did a bit of trial and lots of error and I'm still not happy with the result. I also bought a cl33 body off an auction site and I've used that as my test bed. I have had better results with that, but still lots of room for improvement before I start on my JLTRT locos.
All I can say about building the JLTRT kits is go for it! I was really hesitant at the start but there is so much help on here that you can (with a bit of effort) produce something (in my opinion) that is much better than any RTR manufactured loco. Additionally, you get the satisfaction of having built a loco that is exactly as you want it, not 'off the shelf'. All I can say is do it, you won't regret it.
I will never buy another RTR loco because of the enjoyment I get from building them, it's just a shame that the kits do work out very expensive.
Cheers
Lee