I have just one REL sub (S/812) and find it to do exactly what you describe. I would love to have two of these subs but physical space and room layout does not permit. My settings are very low, about 40hz, and around 10:00 o'clock on the level/gain. It's just right with bass slam directly from the middle when the recording calls for it.. And deep bass in a big open area when the recording calls for it.
The more I have improved the system over the past year I have found needing to lower the crossover setting and reducing the gain. It's about right, now. However, I tend to believe that after my new speakers arrive (still about 7 weeks out) and are fully broken in I will need to lower crossover by about 5hz. We shall see, or, hear.
Enjoy your latest setup.