Aw shucks, but I thinks its just 2 cents.
Unless something in the 6 needs to go to a shop, shortest path is probably the six.
For the nickel I'd say it will be less fwustrating and more rewarding to be investigating. If you make a leak down setup, its will always be handy.
Failed rod bearing it would be knocking like a bad water pump but shaking the engine a bit more. At least mine was. Power wasn't that down.
Maybe one or more valves isn't sealing.
seems worth investigating regardless.