The Shiva is new new new. So not a ton of info for that one, but it looks sick and I'm going to order one. The Everest is like an XL Karnali IMO. Great for big guys and big gear. The Karnali and Burn both run the same shit, but the Karnali feels like a stable tank that can plow through anything upright and track well with speed. The Burn is more like a sportscar that can carve lines you never thought possible, but tracks crappy and doesn't hold a line as effortlessly, which it makes up for by being able to spin quickly, carve, and surf. To put it another way, you have to work harder to turn the Karnali, and you have to work harder to keep the Burn straight.
I have high hopes for the Shiva. I think it's going to be pretty money.