Its all marketing. Anything they can do to get you to buy their product, whether its deceptive or not. When you're new to audio, you're going to gravitate towards the box with the biggest number on it, because either you don't know any better or ignorance is bliss.
The advantage of going with a larger driver will be ability (in most cases) to play lower than smaller drivers. In this case the Fs, = resonance frequency of the driver of the 15 is 27hz, the 12 is 34hz. You could say the 15 is more 'comfortable' playing lower frequencies than the 12. This can be important in ported boxes where tuning below the Fs can sometimes cause issues. The (2) 12's will have a about 19% more cone area, but the 15 is a tad more sensitive...and would only require 1/2 the power.
The 12s, more cone area and more power.
Exactly what Kush said...the 12's for sure. Make sure what ever amp (or DSP) you get has a variable subsonic filter...it is a MUST for ported enclosures. The Type-S sub in 1.5cubes, tuned @32hz with 600rms will unload and hit xmax at 26hz...if you apply a subsonic filter at 20hz @24db you will control the sub below the tuning freq.
Have you modeled the subs to know when they unload? I recently built a box for 2 older type s 12s, 3.8cf tuned to 37-38hz and they hit xmax at 27hz. Thats in a bigger box with higher tuning which should theoretically unload sooner than a lower tuned smaller box. The new type's have similar tsp properties so I doubt much has changed other than a bigger voice coil for more power handling a maybe a little more excursion.
Thats because due to their low price point they are often used by noobs who don't know what they are doing.
Yup
I was 17 in 82, dude back then you get half a lid for 75 bucks, that is half a brick. With 10 bucks, you could get a six pack of beer, a sandwich with chips, and a nickel bag of dank, and still have a lil over a dollar in change.
