I have a switch that supports jumbo frames (9014) and my 10 Gbe NICS support the exact same (9014).
I can ping 10.20.30.100 -f -l 8000 without a problem but my speeds tend to be slower with Jumbo Frames enabled.
I am just doing a file copy from a 2012R2 Server to a 2012R2 SMB 3.0 file share.
I use SMBmultichannelConstraint to assure that it is using the correct NIC.
I get as high as 9.3 Gbps without Jumbo Frames enabled but I only get about 7.1 Gbps WITH Jumbo Frames enabled.