Do we want to absorb the energy coming from the ports ? My understanding was that it made up an important part of the overall output from the speaker.

I was about to say "I imagine most of the port output will be below 80 Hz so maybe not a big issue for HT" but then remembered that VP180 is probably one of the "most likely to be set to Large in the AVR" speakers out there.

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8