Have you seen that big, long thread containing complaints, and condemnations from Shorai owners. No. Because none exist. I've had Shorais for at least 8 years. They're the only motorcycle battery I buy. A Shorai saved my posterior years ago when I dunked a KLX in a stream on Eglin AFB. I cranked for what seemed forever, until that old KLX came back to life. A Yuasa would have fizzled, I'm afraid. I know there a few guys that don't like them, don't trust them. But that's not me.
Shorais have 2 down sides. They cost more. They don't crank real well right off the bat when they're cold. If you're saving money, by playing with motorcycles, tell me how that can be achieved. If you plug your Shorai into a Battery Tender for 10 minutes or so while you're gathering your riding gear, it will be a bit warmed up, and you're good to go. Unlike a big V2, a 919 doesn't take a lot of cranking power anyway. And, how often do you ride when it's cold?
The upside is they weigh next to nothing, maybe a quarter of what a lead battery weighs. They're smaller. In my experience, they last longer. I think they're a little tougher in that you can drain them lower, more often before they finally wear out. You treat a Shorai a little differently when it comes to charging. Plug it into a Battery Tender until it's topped off. Then unplug it. Don't leave a Shorai on the Tender for long periods of time.