I assumed you were inquiring about subsonic filters, and the 12db/oct and 24db/oct correspond to BW and LR you mentioned. I also assumed you know how a hole in a box works.
"High amplitude signals" = you've cranked it to 11.
"...at frequencies where the port and driver are decoupled" = below port resonance the driver and port go out of phase.
I actually have no idea what you're asking. Neither LR nor BW type crossovers, used at the upper end of the subs to your main speakers, would damage your subs sooner, later, or in whatever intermediate time frame you care to mention. Your question just doesn't make sense.