Well I did a output curve, I can do excurision, impedance, spl limit if you like, but I believe the most important is output.
Unless your an SPL freak then even a 6th order setup would be better than a 4th order, I will email you the plot, as you will see that taking a single brahma 12 slot ported has a better output between 20Hz to 100Hz, where a 4th order (bandpass) has an output peak between 30Hz to 60Hz. At 20Hz, ported is 4 dbs louder than bandpass, At 40-60Hz, ported is 2dbs louder than bandpass, at 70Hz, ported is 3.5 dbs louder than bandpass, at 80Hz ported is 6dbs louder than ported, so just by looking at the output, ported is louder than bandpass. I emailed you the graph, if you can post it I would appreciate it so everyone can see a comparison. That being said bandpass is exactly what it says it pass a certain frequency depending on tuning an allows the sub to play that frequency without over exerting the sub, but a slot port tuned low will sound better and still not work as hard. I have owned sealed, bandpass, ported, used the same same in all three enclosure and determined that I like ported. You said a properly tuned box, I haven't seen anyone on this forum building a bandpass enclosure to spec for their sub, they are buying prefabs, and YOU know you cant just throw any old sub in there.
If anyone would like to see the graph give me your email so I can send it, I cant post a word doc on here, or can I?