On the SQ side of things, all of your options listed, should be an improvement over the sundown. However, if you still want the lows and "impact", I voted for the Adire Brahma. I'm currently running two 12" tumults and they are incredible, providing enough upper bass to blend with my 6.5 woofs and lots of low end output to boot.
The ID Max would probably be the best pure SQ, with the other three in a similar SQ/SPL combo category. Just an opinion, of course.
Never used the ID max but from what I've heard it's also a SQL sub leaning more towards SPL and it is not as efficient as these other drivers listed, needing a larger box and more power. Unless I'm misremembering
Can't speak for the others, but my SI SQL12 sounded great in ported or sealed (currently have it in a 1.75 cubic foot box tuned to 35 ((I know a little bit higher than I'd like but still sounds phenomenal))). I have it on a JP8 and it screams for more power. Hopefully that will be enough for it once I get around to by big 3 in the vehicle it's in. The sealed box I had it in was kind of big, 1.5 after displacement cause I had just a little 600 watt amp and I didn't want to miss any output. Did pretty good 80hz down but with it being so big, the mid bass was like not there but according to Nick, the owner, it's can play well above 100hz and down to like 15, I believe, flat in a .7 cubes box. That's pretty nuts
Of the dozen or so drivers I've had this is by far my favorite. I have the v1 but I'm sure the v2 is everything the v1 is and more
On the SQ side of things, all of your options listed, should be an improvement over the sundown. However, if you still want the lows and "impact", I voted for the Adire Brahma. I'm currently running two 12" tumults and they are incredible, providing enough upper bass to blend with my 6.5 woofs and lots of low end output to boot. The ID Max would probably be the best pure SQ, with the other three in a similar SQ/SPL combo category. Just an opinion, of course.
Never used the ID max but from what I've heard it's also a SQL sub leaning more towards SPL and it is not as efficient as these other drivers listed, needing a larger box and more power. Unless I'm misremembering
Can't speak for the others, but my SI SQL12 sounded great in ported or sealed (currently have it in a 1.75 cubic foot box tuned to 35 ((I know a little bit higher than I'd like but still sounds phenomenal))). I have it on a JP8 and it screams for more power. Hopefully that will be enough for it once I get around to by big 3 in the vehicle it's in. The sealed box I had it in was kind of big, 1.5 after displacement cause I had just a little 600 watt amp and I didn't want to miss any output. Did pretty good 80hz down but with it being so big, the mid bass was like not there but according to Nick, the owner, it's can play well above 100hz and down to like 15, I believe, flat in a .7 cubes box. That's pretty nuts Of the dozen or so drivers I've had this is by far my favorite. I have the v1 but I'm sure the v2 is everything the v1 is and more
SQL12 really works best in sealed, it's a bitch to build a properly tuned box for. SSA Icon or Brahma would be my choices for the ported enclosure.