Switches for Small Storage Spaces Direct Cluster Hyper converged environment

That 4500 Router is a beast.

My research is leaning towards IWARP, the speed limitations from Stacking or Binding still exist, but this is disk write and I/O is limited.  My primary concern is uptime, that is why we were moving to S2D.  That said, I really APPRECIATE your very thorough responses.

What are your thoughts about IWARP, much more Switch Independent and seems to get r done.

My current thoughts:
1.  RDMA in a Microsoft S2D Cluster wil be worth the extra costs.  It is a small cluster, 3 or 4 nodes, All SSD DIsks, will be Hypervisor 2019 Server Data Center with 512GB RAM Each Node, Supermicro with two E5's 16 Core.  So plenty of local power, but will be a bit taxed because going with 3 way mirror.

2.  Loved the 4500MX but it is out of budget.  Currently have a XS716T that has been working great up until this point.  If I can connect another XS716T and they can be crossconnected at 20GBe I would probably never have I/O issue.  Which brings up two seperate questions:
      a.)  Would the XS716T be good enough for IWARP with Chelsio Boards.  It would be limited by the interlink.  Have Intel in there now X710-T4, will move those over for VM's and Management functions.
      b.)  Would it be better to get two M4300-24X or 16X.  We have two LACP configured 48 Port Netgears in a Stack now, 1Gbe for Virtuals. 
      c.)  What is the maximume stacking speed on the M4300 Series Switch.

3.  I have to have two switches in case one goes down, therefore, I believe the interlink is very important.

Side Note:  I am moving from RAID 10 DIRECT DAS on the Servers with Replication, this solution is very fast and has not failed.  ALL SSD Storage.  It replicates with another server.

My partner makes an Excellent Point, with the Replication we can be up quickly, and all this complex configureations is simply to avoid DOWNTIME, something we have not had to this point with our simple but powerful environment..