What are the advantages of suiteanalytics connect vs a restlet that executes suiteql passed in as a parameter and returns the results? Is it the same schema?

the ODBC schema differs. I think the REST schema is supposed to be the same. A potential advantage of using the pre-built connectivity is they can better optimize for it than a custom restlet.

Which schema do you think is better? For example getting a breakdown of inventory by bin, lot and item has proven impossible in suiteql. Even @tdietrich couldn't help me.

ODBC has two schemas available. The netsuite2 schema is supposedly the same as analytics/SuiteQL. ODBC shines in raw speed for simple queries without joins, for example if you wanted to replicate tables in data warehouse.