I had an E-10 and those get loud too on very little power too. If you had the room, you could almost do two (2) E-10s.
But to your original question....I think the SA is a no-brainer. What vehicle is this going in?
If you want that "punch in the chest" feel, get the SA-10 and port it. It will still handle that RF amp.
I had the SD-12. I liked it but it's made for sealed enclosures only.
Incriminator just released their latest and greatest Death Penalty. Would love to see Steve do something sick with it. Inverted surround looks interesting like the Sundown SD and the magnet/boot looks insane.
Do what you wanna do but I asked Jose at D'Amore this EXACT same question and he told me to set the gain knob (if you have one ) to max and set sub output to max. I've only set one car with my DD-1 one time. These other guys are way more experienced than me on here so take my advice for what it's worth.
I set mine like strangeduck did with the exception of the sub level at 0.
I wrote to D'Amore with this same question.
Set sub level to max (+6 in your case) to set with DD-1.
Afterwards you may want to back down a little bit to blend your subs. I did and was very pleased.