"Acoustic suspension" is just a fancy name for a relatively small sealed cabinet (as opposed to a sealed cabinet so large that the air doesn't actually act as a spring) .
(Many
very early speakers had relatively large, thin, or poorly sealed cabinets... which didn't really count as sealed enclosures for modelling purposes.)
In general, "all else being equal", for a relatively small cabinet...
A sealed speaker will start rolling off sooner, but will roll off more gradually, and deliver useful output down to much lower frequencies...
A ported cabinet is usually tuned such that it is flatter, and delivers more bass efficiency down to its tuning frequency, but its output drops off sharply below that...
(Modern tuned port speakers are usually tuned to quite low frequencies... which enables them to deliver low bass... but many older speakers were not.)
Also, and really important back in the days of vinyl, but not a big deal today...
With a sealed cabinet the woofer will move less at very low frequencies; its movement is limited by the "air spring" of the cabinet volume.
A ported speaker is the exact opposite; the port tuning controls the woofer's movement at the tuning frequency but offers no control at all below that.
As a result, while the woofers on tuned port speakers have little usable output below their tuned frequency, they tend to exhibit more motion at very low frequencies.
Because of this, and because the RIAA equalization used on vinyl boost low frequencies significantly, a warped record will often cause a
LOT of woofer movement on a tuned-port speaker.
(To the point where it can not only cause clearly audible modulation noise but can actually destroy the speaker.)
Modern speakers handle this somewhat better than most older speakers; and modern turntables seem to handle warped records somewhat better as well.
The idea with three-way speakers is that it is difficult to create two drivers that can handle the full audible frequency range well.
(The design requirements to optimize a speaker drive for low frequencies, and for high frequencies, are almost directly opposite each other.)
As a result, speakers with woofers large enough to deliver lots of low bass, and tweeters small enough to offer good high frequency dispersion, tended to have trouble in the midrange.
(For example Larger Advents, which were two way speakers, were notorious for having prodigious low bass, and "pretty good highs", but being "a bit weak in the midrange".)
The drawbacks of three-way speakers are that more drivers cost more, they require a more complex crossover, and the design itself is significantly more complex.
(You have three sound sources, which can interact with each other and the cabinet, and which overlap in two different frequency ranges.)
This means that, while in theory a three-way speaker can perform better, it's more difficult to "get it right", and there are more ways in which you can get it
wrong.
