Bill,

It is really not strength that is necessary. Stiffness is what you need. Steel and cast iron should be virtually the same, if the thickness and shape are the same.
I have a friend with a nice looking (can't remember the brand) steel saw, but it vibrates badly. Closer examination shows it has a C section frame, not a box and it has seriously less stiffness. We have talked about adding a narrow C to the open area to get the stiffness back, but he is so depressed at the money he wasted we haven't started.
If you look at the stiffness modulus of steel is ~30M, cast iron at ~ 20M, and Oak at 1-2M you can see you would need a much bigger piece of wood. Of course the vibration would be damped out more with the wood.

All that says I agree. Wood should be relatively poor.
If you just want something for light work it could be OK but not good.

Marc

: Have to agree, it's one of the problems of the steel welded frame
: of some of the newer bandsaws is the frame isn't strong enough
: for enough tension on the blade, getting that from a wood frame
: would be a real trick. And the wood would stretch over time
: loosening the blade further, cast iron really is needed for the
: frame.

: Bill H.