OBS aren't quite right until a PID is added.
I have a SS OBS and have used it for several years just as it came out of the box, only additions are a Maverick ET dual probe thermometer, some jerky racks and bubba pucks and it is BRILLIANT!
Yes the PID may add some bells and whistles and improve performance somewhat but make no mistake, you can get superb cold and hot smoked food out of a bog standard unit. IMHO smoking is more of an art than a science and the OBS caters for that.
I am sure there are plenty of people who will say otherwise but given the choice again I would stay with my plain SS OBS.
I don't have any experience of the digital unit and will leave that to others.