The GS3 & GS4 are beautiful locomotives whether plain black and stripped or in full dress with Daylight colors! Maybe it's time to petition AZL to do another production run! Last time they wanted 50 committed pre-orders... I think we got about 40... Should we try again?!
Since Rob A. is telling us there is currently no brass shop, does it really make any difference? I would suggest looking into the possibility of doing a GS-6. Then you would have the WP 480-series locomotives for additional prototypes. I know Hans had said that the GS-6 wasn't feasible when they did the GS-3/4, but times have changed.
Personally, I would be interested in one SP unit for the San Joaquin Daylight and a WP unit.