I have found very interesting comparison Aerospike VS Cassandra. Aerospike looks very interesting however there are still some open questions. For example Scylla says they faster than Cassandra in 2-5 times. Another point is 64 bytes per key - it is a lot, so intresting to compare in ALL-FLASH mode.
So I would test Aerospike vs Scylla but unfortunaly by default trial version just for 1 node. But much more useful find out how to work PROD-like Strong Consistency mode. I wrote to info @ aerospike.com but have no answer.
Could you please give some contacts which can provide trial version for 4 nodes?