We have been using hard maple for all of our maple kitchens and millwork for years and now our lumber supplier is suggesting the use of soft maple instead. What has been your experience when using soft maple? In a related matter, I have an architectural spec calling up material for a large run of cabinets as "hardwood" and in the subsequent color schedule as "maple". Would you consider soft maple for such an application, and would you ask for clarification before doing so? The cabinets have glass doors with narrow little frames so I would rather use the soft maple for reasons of warpage.
You didn't mention whether the project was paint grade or clear finish.
Many of my fellow cabinetmakers and I use soft maple for paint grade face frames and doors. Itís a lot harder and more stable than poplar, while costing roughly the same. It also gives a better paint surface due to its hardness.
The primary difference between hard and soft maple is obviously hardness, but also color. The hard maple you buy should be 99% white sapwood. The soft maple often comes in about 50-75% white sapwood with the remainder being a gray/brown heartwood. This doesn't present a problem if painting, but clear finish looks terrible.
As far as the specs concerned, I would certainly verify the species if possible, especially if you think you might go with soft maple.
You also mentioned using soft maple for muntins to avoid warpage. I don't believe you'll get any improvement over hard maple in that regard.