I agree that a 15 or 15 clone would fit your requirements. They are all metal, have a generous throat space, have a reverse stitch, and use low shank feet. Billy says that some of the clones are actually better machines than the original Singer 15. My clone has a 1.0 amp motor and is the quietest machine we own - even quieter than the FW. It was made by Brother and is badged as a Compac.
You might try poking around in thrift stores, antique stores, yard sales, and estate sales and just see what is available. You may run across something that speaks to you. You can usually pick one up for a very reasonable price, and if you don't like it you can probably sell it here or on ebay or Craigslist.
I also have a Rocketeer (503) in a cabinet with knee bar and love it. I have pieced two quilts with it and so far it is my favorite vintage machine that we own.
Good luck in your search.
Darren