Hi, You can get the spec from competitor's data sheet which can found at offlical website. I can share some of spec to you.
1) HPE, Primera 650, support 4 controllers, 48 NVMe drives which is same as FS7200 with 4 controllers. Primera 650/670 only support 4 controller per cluster. Primera don't have NVMe expansion too.
2) HDS don't have NVMe drives in mid-range AFA.If you want to compete with VSP 5100, the maximum NVMe drives is 96 /w 4 cotrollers.
3) Dell-EMC Powerstore 5000/7000 T model has similiar cluster as FS7200 that support 8 controller per cluster. The appliance(2 controllers) support 25 NVMe slot but only support 21 NVMe data drive and 4 NVRAM drives(Write cache).
Hope this can help.
------------------------------
JUN ZHU
------------------------------