Welcome fish!
The only thing you can really do is take advantage of Axioms 30 day trial and compare them side by side. You could always see if a fellow axiomite close to you would have you over for an audition as well.
The only issue with that is you would be listening to "their setup" "their room". A true comparison would be to have the M80's side by side to "your" HPM 100's and "your system".
I too waited 20 years before I upgraded my vintage Boston Acoustics A100 bass reflex speakers to the M80's. I will tell you it was a HUGE difference for me. I'm totally content with the M80's for sure. Over a year later, the M80's still surprise me.
Your pioneer HPM 100's are for sure very nice speakers, they don't make them like that anymore and actually you may be in for a tough time adjusting to "any" modern day speaker. Only you can be the judge, but for me, I can't believe I waited so long to upgrade.
Fair warning thou...once you get the M80's, be prepared to go into a spending spree for the rest of Axiom's speaker lineup...
Dana
