Other than changing the oil or valve pump it is pretty impractical to rebuild the "disposable" semi herms in the field.
Open drives, of course, are the original design dating back to the early days of York and Frick.
Back then everything was big bore, long stroke, and slow speed. Semi hermetics came later as a cheap alternative to open drives.
Also, fewer moving parts than the vilter 440/450 compressors. Been taught how to replace shaft seal and did 1 alignment.
Sorry for the long post, but it really boils down to knowing what you need for your refrigeration and then backing into the strategy that is going to be the best. A friend who works for a competitor just installed a bunch in a meat plant running 407a..the motors were run off yaskawa vfds.
I know that open drive compressors are used for ammonia refrigeration applications, But are there any other advantages or reasons i should choose an open drive compressor?