I usually buy the premium vehicles from the WB shop before anything else. The KM-5 was one of only two WB vehicles I didn't already own in the shop, so I decided to try it out. My god, this thing is terrible. It's got worse firepower than many of the German coastal 1.7 vehicles, and you face a bunch of boats with 40mm Bofors that just shred you to pieces. Wish I could get a refund.
I'll own up to the mistake of buying this thing, but Gaijin are also scummy as hell for putting in a rank I coastal worth only 400GE and charging 2500WBs for it. I remember before the WB shop/Battle Pass integration, the vehicles in the pool refreshed every month and usually offered all rank 3s at minimum (and the occasional rank 4). We've already reached rank 9, yet it's not only just the Battle Pass itself which is getting worse and worse, the WB shop is a mere shadow of its former self too.