i agree with martin crabtree ... no use hanging onto stuff that takes up space
doesn't get used ever and maybe someone else could put to use ...

but ...

does your toyo whole plate camera have the movements you may need to shoot architecture or table top stuff?
is there a reducing back so you can shoot 4x5 instead of 6.5x8x5 / 5x7 ?
if you are going to use it as a back up for your sinar i'd worry about the format ...

i have a toyo cx that i use for my 2-4x a year film based architectural-work and had thought of
selling it and using my 5x7 instead with a reducing - thing, but i realized that
the toyo was more "flexible" took less time to set up had a bag bellows so i can use a wide ( 65mm ) lens &c.
i'd sell it ( like you are thinking) if there was a pro-shop near me that rented 4x5 gear ... closest one now is 1.5 miles away

while i think it is good to clean-shop sometimes and sell things you don't need,
the sinar is a work of art, and it is versatile ... and maybe more useful than the toyo in some situations ...
( if the back is rigid or doesn't afford movements / allow you to reduce to a small negative ).

tlrs + ikons will sell light hot cakes !

have fun with your sell-off