Kinda tough to say sans pricing.
As for the speed of the ECB6200's, I'd assume that you're planning on installing at least a 3 node setup, so max shared throughput for the 3+ node bonded MoCA 2.0 network would be 800 Mbps. That's 800 Mbps shared between the forward and backward paths for each active connection; if you won't have much competition for throughput, it should be fine. (But, again, go/no-go would still depend on the price, I'd think.)
For comparison, a support-less
Frontier FCA252 MoCA 2.5 adapter with 2.5 GbE network port can be had for $30 per via eBay.
edit: Related info: