I have the Shockwave and not much has changed for the new ones. We really like it. We had a couple of warranty issues when we received it. It had a scratch in the bedroom ceiling, the stabilizing jacks weren't affixed to the frame very well, and I had a USB charger go out. Those have all been fixed. Had a small leak on the black tank wash flush (freshwater side) that I just tightened. That's it.
The tankless water heater is a love/hate relationship. It's finicky to adjust, but once you get it right, it's nice to not worry about running out. It's definitely noisy. You can opt for a regular 6 gallon.
If I had to do it again, I would've got two benches instead of the recliners. But we love the room in the kitchen and the walk around queen. The toilet's a little tight. The shower is awesome.
I haven't had any issues towing it other than my tow vehicle being blown around, which I'm in the process of rectifying.
The Sandstorm and Shockwave are twins. If you have any other questions about them, let me know.