On a stock S9 I can confirm that the LPM firmware either modifies or replaces the bmminer file, I would assume it would replace a modified bmminer as well.  The LPM bitmain bmminer does not work with slushpool.

I added Taserz bmminer after the update to LPM and it does work with slushpool.  This modified bmminer seems to run faster with LPM checked, maybe someone else can confirm this, I don't have time to check on multiple machines at this time.  bmminer880 650 freq 13.950 th/s.  With LPM unchecked I see readings closer to 13.825 th/s.  I don't have access to power readings at the moment unfortunately.