Matt, if Bob doesn't mind I can comment on the KEY E-6's and Bob can comment on both. The last run 2014-15 (might be the only run) of the KEY E-6's are a knock out. The Santa Fe units were especially nice and there are photos and videos of them on the internet. I know Gary Schrader had several videos and you can still see some great photos of this model on the KEY website. Gary was involved in the correctness of the build, just as he has done on the new KEY AC's, which are incredible.
OMI imported their E-6's and E-3's maybe in the late 80's or early 90's and they had tank drives. I don't think they repeated this offering again. They were imported in natural brass finish and required paint, lighting, glazing and drive updates. Highly detailed Samhongso or Ajin models, like most OMI diesels, but required the modeler to finish them.
The KEY E-6's are beautifully factory painted, lighted, glazed and had a new improved drive, designed by Roger Lewis (Wasatch Models). They had illuminated work lights above the trucks and really neat Marrs light plus cab,instrument panel and engine room lights with simulated prime movers (highly detailed and painted brass panels) you can see through the side screening. They also ran as smooth as any model out there and quiet as a Swiss watch. They are DC only as getting a consensus on which decoder to install was impossible. But adding your own decoder is not that difficult.
All in all, a real home run of a model. Due to limited years of prototype operation I've seen them on the secondary market, brand new, for much less than they cost the original owner. But, you'll still spend $1000-1250 per unit. In the long run these are the models you should shoot for. More expensive that OMI's, but your buying a 21st century designed and built model in all respects.
Hope this helps.
Butch
