I don't have any production experience running Clickhouse, but I have used it on a side project for an OLAP workload. Compared to Postgres Clickhouse was a couple orders of magnitude faster (for the query pattern), and it was pretty easy to setup a single node configuration compared to lots of the "big data" stuff. Clickhouse is really a game changer.
There's replication in ClickHouse and you can just shove reads off to one of them if you'd like. From a backup/safety standpoint that's important, but I think there are other options besides just replicas, of course.
From an operations standpoint, however, ClickHouse is ridiculously efficient at what it does. You can store tens of billions, probably trillions of records on a single node machine. You can query at tens of billions of rows a second, etc, all with SQL. (The only competitor I know of in the same class is MemSQL.) So another thing to keep in mind is you'll be able to go much further with a single node using ClickHouse than the alternatives. For OLAP style workloads, it's well worth investigating.
