In my listening space the KUBE allowed me to not have to run a sub and I never missed it. In fact, I started using the KUBE with other speakers so much that I just removed the sub all together. That's doesn't mean you will have the same experience, but that's what ended up working for me.
If you're local to SW Florida, you're welcome to try out my KUBE and see if you like it.
I'm not 100% sure on this, and maybe it's because I use smaller wattage receivers, but with the KUBE on, they seem to run out of steam quicker than without it... so I can't play the music quite as loud. That's fine for me 99% of the time but maybe not for you. And maybe that wouldn't be an issue if using it with a larger receiver. Unfortunately I don't really have anything bigger except my HT receiver, and I don't feel like messing with that.