Extremely interesting posting. Actually there is no correct answer because it depends on what you are playing and where you intend to play it at.
A true bass purist and snob, actually think playing a bass with 10's takes away from the bass line. Heresy these days because the Ampeg 8x10 for some reason has become the industry standard. Couldn't think of a worse way to play a 10 inch speaker either, because they are closed port and you have to drive them with wattage. That is not how a Sunn should be played, because "in the day" 100 watts and a front ported cabinet was a bad ass rig.
Because there are two ways to create and maximize sound using a speaker. First, making sound with a speaker (or as Sunn appropriately puts it, a transducer) involves converting an electrical signal to a mecahanical device (i.e., speaker)that moves air. There are two ways to move more air, make the wave as big as you can by adding more paper (or, by using a "ported cabinet doubles the sound because it develops the speaker pressure wave from the front and back of the speaker), or "drive" the speaker with higher wattage to force more air to move faster (kinda). And, conversely, if you ram 1000 watts through a Sunn cabinet intended for 200 - 300 tops, the speaker has no resistance to the force of travel, thereby blowing your perfectly good paper speaker all over the room.
So which one? And does the 10's or the 15's sound better? Again, goes back to how and what you want to play. And they do sound different. I had Ampeg 8x10, hated it and practically gave it away. I use 215B Sunn cabinets and I love them. There is nothing like a 15 when it is moving air from my EV SROs (yes I am old school) at 27 Hz and the cabinet doesn't sound like a mud pump sucking slime out of a pit either. 15's (in my HUMBLE opinion) are the choice for bass because they have a lot of presence because they are so low.
