Totally agree with Dell's comments above...I was part of the 4.2 BETA in September, but not taking part in the "Ramp Up" - so I can't comment on anything that has changed since then.
In general, if you are NOT using BEx queries, HANA or .UNX universe as a Data-Source, there is no reason to use CR4E.
If you are using Relational DB as your Data-Source, or you intend to use Custom Crystal Reports (via ABAP List Views) in SAP ECC - then you should stay on the CR-2013/16 code-base.
There are still a lot of Functional Design tools in CR-2013/16 that have not been included in CR4E yet.
For Example - https://ideas.sap.com/D30934