The load on the source and target hosts and memory used by the VM are the bigger factors than the vMotion network speed in affecting vMotion eprformance - my experience with lightly loaded hosts vMotion should be less than 20-30 seconds from initiation to completion
I'm not sure what exactly you're looking for here. As you're surely aware of, this depends mainly on the memory size of the VM and especially how fast memory pages change within the guest during the migration. Due to the latter being extremely unpredictable and dynamic, it's nearly impossible to calculate accurate guesstimates.
vMotion traffic is uncompressed and easily saturates a 1GbE link, so with a bit of protocol overhead and physical limitations in mind, you should be able to transfer ~115MiB of VM memory per second (I usually see around 940Mbit/s raw link utilization in my environment), not factoring in delta transfers due to changed memory.
A few years ago a performance study, sponsored by VMware, comparing ESXi5 vMotion with Hyper-V live migration performance was released. It contains a few numbers you might could use as a very rough reference:
In the end, you will have to resort to some testing on your own in a environment with workloads as close to the target environment as possible if you want numbers you can trust.