I think you should use amd64 CPU boxes if you want 300mbps v2ray performance - you can get aliexpress dual lan boxes for about the same price as the mt3000 (80-90$) not to mention second-had boxes that should be about half price
MT3000 can do around 300 Mbps Wireguard. However, that isn't recommended, because there's no CPU room for anything else. Maybe MT6000, if v2ray is multicore, could do this.