details... details...

"Can etf's have a hidden penalty over mutual funds if you decide to
xfer
to another brokerage account? "

No. If there's a "penalty" it's an account closing or transfer fee
charged by the losing brokerage firm. The etf transfers like any
other listed equity.

"Besides xfer fees for an account (free for Scotty but usually $50 or

so), I commonly see fees listed for stock certificate reregistration,

xfer and ship. These can be $50 per certificate; would this apply to
etfs held by the broker (no paper certificate that I'm aware of)? "

Those are two different types of fees (account transfer fees and
certifacte related fees). If you have a brokerage account there's no
need for you to have certificates or face any certificate related
fees.