I had a skate banana when they first came out and that thing sucked... a complete noodle.
Do not think it sucked. Good board for its purpose and sure helped me become a better rider - but definitely soft (especially after 3 years of hard riding) and not what I am currently looking for.
If i remember correctly, your other options are all still true twin, ec2 camber with similar waste widths... why not go for the stiffest of the 3 to complement the banana?
On a somewhat related note, the Never Summer Proto seems to be EXACTLY what you're looking for, and more.
I think it is time to replace, rather than complement the Banana. Ideally with a more versatile board for everything but the most epic powder days (got a Sick Stick for that).
Have heard good things about the NS Proto. Not sure what the best price for one would be?