What are the advantages & disadvantages of moving from medium format to a full frame?
2 disadvantages of moving to full frame would be (1) less dynamic range which affects how much detail is retained in the shadow and highlight areas of your image as well as color accuracy is much better with medium formats. color accuracy affects, for example, how natural skin tones look. (2) typically less resolution on full frame images. Images just look sharper when shot on medium format.
If you are still shooting Medium format, I wouldn't hang up the cameras just yet. There's plenty of life left in them. If you've never shot medium format and want to know if it's worth it. I'd say it depends on your budget and how much of a stickler you are for capturing what you saw on the day. FF DSLRs are advancing so quickly that there is really very little reason to pay the super high prices for medium formats.