Dave, glad you are pleased. Addressing some of your points:
2. The model prototypes were thoroughly tested with all combinations of truck-mounted rolling stock through various radii of track without issue, so there should be no problems running the G26 with any current existing equipment.
4. You are correct, it would have been four extra paint hits and pushed the MSRP higher than $26.95 (which already is higher than initially planned for). Fortunately Microscale makes the proper decals. The paint color is the proper PC Deepwater Green, with paint samples obtained directly from the PCHS.
5. The inner rivets serve to hold the ends in place, so there was no need to add "retaining bumps" as is used on MTL drop end gondolas. If the "flopping" is an issue, ESM will replace the car for you if desired - just drop me a PM.
6. It's as heavy as possible without compromising the detail and where the height of the floor should be in relation to the rails (and the side rivets). The facts that the center of gravity is so low and that the car has body-mounted couplers adds to the car being able to perform well. Good trackwork doesn't hurt either.

Hays Bros has released a number of loads for the G26, with more to come.
There is another Pennsy-specific prototype on the schedule, but it's the third car in line of those to be produced. The XIH is next, most likely followed by the well car. Look for the Pennsy car in 2011/2012 if someone doesn't beat me to it. Either way, you will be pleased.