You will lose tightness, and you will lose bass. Quite a bit, actually.
It's going to get even more mids, just shifted down some into the low mid territory. It's not quite as buttery as a CC, but it's in the ballpark.
If you're into playing big thick leads, this would be your pickup. If you need big, tight palm muted rythms, the C5, standard JB, or Custom will do it better than a JB II.