Complex sentence: Yes, I concede that "the Pratt-Romneys" is not a term that tends to slips off of anybody's tongue, anywhere; nevertheless, when insiders talk about the Romneys they "mean" the Pratt-Romneys.
Split into simpler sentences: Yes, I concede that the Pratt-Romney is not a term that slips off anybody's tongue anywhere. Still, when insiders talk about the Romneys they "mean" the Pratt-Romneys.