Very cool! I've got an earlier version of the NS Designs upright (it's called the CRM-4). Good sound, but it's hard to keep the bass and stand from wobbling, especially when playing with the bow. I have to put one of my feet on one leg of the stand to keep it kinda sorta steady. Back on topic, I'll bet the Rumble 500 handles both of those big guns just fine.
This stand is pretty sturdy. Haven’t had any wobble issues. And yea, sounds great through the Rumble. I usually use a small preamp that attaches to the back of the bass. Gives me a bit more output and low end. But didn’t use it tonight, but still sounded fine.