There were two Schiedmayer companies: J & P Schiedmayer and Schiedmayer & Sohn; different branches of the same family. Schiedmayer was a quality brand before the Great War. I owned a J & P Schiedmayer 170 cm, 85 key, two pedal grand built in 1913. It was a fine small grand with lovely tone, similar to Steinway. I've played a few BlĆ¼thners, and while fine pianos, I'm personally not wild about their tone, which is too mellow for me...but is to many people's liking.
Before buying, and because the pianos you are considering are old, have the piano thoroughly checked over by a piano technician so you know if the piano needs any major work. Most will need tuning and regulation, which is standard, but if the piano has a bad pin block, or badly rusted strings, or a cracked bridge, or a sound board that buzzes, or mouse droppings in the action, etc., then you are facing major repairs which are expensive and usually not worth the investment on these old pianos.