Losing Spirit Surge on the Medium means you lose the lesser power and seance boon of Marshall entirely yes?

[HibikiSatsuo]

Just want to confirm this is the case. If you take the Spirit Dancer or a similar archetype that replaces Spirit Surge it means you lose most of the benefit of the Marshall spirit type since it requires you to use a class feature you don't have right?

[Markov Spiked Chain]

Spirit Dancer doesn't replace Spirit Surge. If you're channeling Marshal with it, you can still Surge.

And nothing about the Seance Boon is tied to Spirit Surge?

But yes, if you lose Spirit Surge, Marshal's lesser power is a little pointless.