Don't store ugens at the top level of Inst and Synth records - they're already in the :sdef slot.
No need to add an empty :args key - this doesn't do anything useful.
Modify AudioBus and ControlBus print formatter to print a default name and to label the attributes more clearly.
Unify ugen name in debug namespace to Overtone style name - and also replace Binary/UnaryOpUGens with appropriate names: *, +, / etc.
Make control-ugen a specific type rather than plain ugen to ease debugging. Ensure that control-ugen derives from ugen.
Add some explicit type checks for synthdef manipulation fns.
Add new helper fns: node-destroyed-event-key, node-created-event-key, node-paused-event-key, node-started-event-key to discover the event keys for the node manipulation keys. Also add helper handler fns on-node-created, on-node-paused, on-node-started to make it easier to add fns to handle these events.