Switching from Ranger to Bard - You'll lose all of the "Ranger only" abilities like Auto-search and the ranged criticals, can't equip any Ranger specific weapons either.Also, you may be a level 1 Bard but will need the experience points for a level 16 Bard for your next level up. The game uses "total" character level for calculating the experience needed for the next level-up. So your new level 1 Bard will have a long wait for level 2 as a Bard.
Another note, instruments, and gadgets for the gadgeteer, have both skill AND level requirments before you can use them.
Class switching should be done early.
Spence