Have a 400 SS. The windless/anchor config includes all chain, I've seen this on many Formulas. Anyone know how to cast off the anchor in an emergency? Or even how to do it if you have lots of time?

I would assume that Formula includes the windlass owner's manual with the boat. What does it say?

All you can do is ease up towards the anchor and hold the "up" button. Cutting through the anchor chain will take far too long. Trying the freespool all the chain out will take time as well, and then you'll have to disconnect the bitter end of the chain anyway. Don't use the windlass to pull the boat forward; you'll burn out the motor.

What sort of emergency do you envision?

An emergency such as you come back from a long hike, some weather has stirred up the big lake, the windless won't bring up the anchor for some reason, and you have to get out and away from the shoreline before your drives start churning up sand and zebra muscles.

You could go to a chain/rope rode, where only the first "x" feet are chain. You might have to change the capstan on your windlass to handle to rope/chain combination. A good sharp serrated knife, and you'd be out of there.

Not sure if this helps, I had my anchor caught on a submerged root wad with a huge storm coming. Ended up letting all 150' of chain out, there is a shackle on the bitter end connected to the boat, I tied a fender to it and let it go. Came back after the storm and retrieved my anchor and chain.
The chain went out very fast.