We’ve had an NVME based PE R740xd system for more than 4 years now. In it’s current configuration it has 24 x 15.36TB Micron 9300 Pro NVME drives. We use it mostly as high performance virtual disk storage via NFSv3. Several years ago, there were some issues around the number of drives the system would recognize, hot swap, and overall performance but those were mostly the result of how new NVME drivers were to FreeBSD at the time and have since been rectified.