We are using Terracotta 3.7.0 opensource for our upcoming product release.
Up till now we used 32-bit Terracotta server and clients. But, right now we tried to use one 64-bit client (java application running at the 64-bit jdk).
The question is - is it OK for Production and what kind of problems we can [potentially] meet???
There are no known issues mixing and matching 64bit and 32bit jvms. The only things that change are how much space an oid requires (which can be mitigated with compressed oops) and how big a heap/offheap can be used.