Food offerings are the same across, last I've been also across Biz and Sen.

SEN lounges have more space, Both for views and for simplicity of connection (if your FCO flight indeed does leave from T2S) I would suggest SEN lounge in K concourse (Schengen Satellite).
However if it happens to be crowded (in case it is still running as single lounge - I would think not, but have not had confirmation otherwise) you can take the train to G concourse. Only one of two Senator lounges is open there, but it's spacious enough and the collocated Biz lounge is open as well, so there is not sending Biz pax to SEN lounge on that side.