Hi Tim,
I am very familiar with both of those.
The larger Advent is a classic, a best seller in it's time. Served me faithfully back in then, cranked to the limit while I jammed along on bass guitar. Eventually the woofer surround rotted away though and they went out for the garbage one night but someone scooped them overnight before the collection came. Kind of made feel good that they maybe were going to be used again :)
The M3Ti won't reach down as deep due to the physical size difference but will have much more extension in the high frequencies with tremendous more openess.
I am not positive of the spec on the Advent but I think they started to roll off around 12kHz in the top end. They were relatively innefficeint too, about 86dB if memory serves (I think they used to have a white label on the back at the binding posts that showed some specs and a curve measuring something).
I'm positive that you will not have to turn the volume up nearly as much with the Axioms to hit the same volume levels.
Also, technology has changed greatly since then so you will hear much more detail and a lot less colouration. Granted the bass won't be as deep but it will be a lot clearer and faster with a lot lower distortion.
Hope you find that helpful.
Marc
