How big is your cluster state? How much is too much?

Everyone knows that a big cluster state might be a problem, bug how big it can safely go? How much is "too big" and how much is "ok"?

I guess this depends a lot in the network bandwidth between the nodes, but I would like to find some sort of formula that can answer the first question here.

So, I would like contributions to collect some performance numbers using the following command-line. Maybe we can find some sort of general threshold:

My reference cluster has 10 nodes with 7GB heap, and SSDs, all nodes are connected with gigabit interface. The current performance is good.

ES=es-node:9200 time curl -s http://$ES/_cluster/state?pretty | wc -lc
  62955 2540673

real   	0m0.087s
user   	0m0.000s
sys    	0m0.008s

ES=es-node:9200 curl -s http://$ES/_cat/shards | wc -l

I have read some information about this topic at somewhere in the official guidance.

Where? (off course I already searched for it)

Oh, I may make a mistake. I can't find them in the official guidance.
I have recently read this in this blog