I really don't think your usage suits a birdie ( I have own its not bais), birdie is a light weight compact folder that excells on tow paths etc. Parts are difficult to get quickly alythough more are generic than some folders.
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Sanu recomemdation of two wheel sets on the folding mbt sounds solid.
I ran a mountain bike with two wheel sets when I only had storage space for one bike. Worked great. Possibly consider lock out forks and you have a hybrid and a mountain bike.