[CentOS] two 2-node clusters or one 4-node cluster?

Hello,
I'm planning migration of current two clusters based on CentOS 6.x with
Cman/Rgmanager going to CentOS 7.x and Corosync/Pacemaker.

As the clusters and their services are on the same subnet, and there no
particular security concerns differentiating them, I'm also evaluating the
option to transform the two clusters into a unique 4-node one during the
upgrade.

Currently I'm testing a virtual 4-node CentOS 7.4 cluster inside oVirt 4.2
and things seem to behave well.

Before going further in deep with tests and so on, I'd like to check with
the community about how many CentOS 7.x clusters composed by more than two
nodes are in place and what are the feedbacks on them in terms of
incremented latency/communication, ecc scaling out.

Also general feedback related to CentOS 6 and scalability of cluster nodes
number is welcome.

Thanks in advance,
Gianluca