The brunt of this discussion is happening on the Yahoo P:48 modelers group list. Some good discussion about whether to add things to the kit that folks might not want, like Kadee couplers.
Decals are a hot topic and I would guess that with so many P:48 modelers wanting these cars the quality of the added details such as ladders and brake systems will have to be good and be accurate.
The SAL box car is still falling short of reservations but the 70 ton AAR low deck flat has sufficient interest to be produced.
Hopefully both will make it.