sealed vs vented subwoofers

Do the sealed subs produce a higher quality tighter controlled bass vs a more sloppy reverberating type of LFE out of the vented types?

Yes - just like most speakers - when a vent is used to extend the bass of a small box it increases the group delay and you lose accuracy. What most people are not aware of is that this ruins the lower midrange because a ported sub will "mask" other sounds that you would normally be able to hear.
(this can affect sounds several octaves higher than the sub and it is due to the way hearing works)

Compare the same sub from HT Shack Subwoofer Tests sealed versus ported.

Although the ported sub plays louder with lower distortion it goes on making noise (rings resonantly for up to three extra cycles). Note how the spectral decay plot has a camel hump - be wary of any sub or speaker that does this - it will tend to give you one note bass. (unfortunately it is the most popular design as it sounds impressive and fools people into a purchase based on a stereo showroom listening test versus more accurate speakers/subs)

I believe that the room plays a dominant role in the bass region, and one of the things that rooms tend to do is boost the very deep bass due to boundary reinforcement. A sealed box sub generally gives better synergy with this room-acoustic effect because of its typically higher-but-more-gradual rolloff characteristic. A comparable vented box sub usually goes deeper, but the room's inherent bass-boost often results in excess deep bass energy and a bloated-sounding bass characteristic.

There are exceptions to these generalizations, so I recommend evaluating subs on a case-by-case basis.

Duke
dealer/manufacturer

You cannot ruin the lower midrange with a sub if you cross it over properly and run it at the proper level. Many people expect the sub to take the place of the woofer in their main system. I use them as a SUB woofer, to add bass below the level of the woofer in the main speaker. I do not run the signal from the preamp through the sub back to the main amp. I have 4 pairs of subs , 3 are ported and they all work well. My RELs are ported and I do not know of a sealed box woofer near their price that I would consider their equal. To issue broad decelerations that one type of design is better than another is almost always wrong. Over the last 30 years I have had a number of excellent speakers and most, maybe all, were ported.

Full flared ports reduce the noise problems with ported designs. I would say both can be made into fine subwoofers. Still for the ultimate in bass for music or HT a bass horn, massive OB design or bass tower sounds best. But they are large costly why most folks purchase affordable subwoofer designs. To me the total design of a subwoofer is flawed from the start designed more for WAF and profits. Less for ultimate perfromance. I would say most loudspeaker designs also fall into this.

To issue broad decelerations that one type of design
is better than another is almost always wrong.

It is simple physics. Sealed enclosures tend to produce tight, accurate bass
with a flatter frequency response curve. They are also generally the enclosure
of choice when looking for sound quality. Ported designs are more efficient
and give you more SPL output - they are generally the choice for higher
output when sound quality is less important. I explained why above but I'll try
further. More technically speaking it has to do with system Q....a ported
design tends to have much higher Q (underdamped) than compared to a
sealed design, again this is physics - the sealed box acts like a shock
absorber and dampens the movement of the cone - this makes the woofer
stop quickly when the power is removed whilst a ported design will just
waffle around even when power is removed. (Of course you have very sloppy
ported subwoofers with port tuned at 40 Hz and much better sounding ones
like the one I showed in the link above which can be tuned at 10, 15 or 20
Hz. Nevertheless, in a sub, the ported designs are always sloppier (higher Q)
than sealed - although a 10 HZ tune will have much better sound quality than
a 20 Hz tune)

You cannot ruin the lower midrange with a sub if you
cross it over properly and run it at the proper level

I guess it depends on your perspective. Most subwoofers typically add 20%
harmonic distortion anyway. There are some measurements on REL
subwoofers on the HT Shack website - so you can compare their
performance to other subwoofers.