Titan is used in a number of production environments, though as of today, Elastic Search integration in 0.3.0 is still considered "experimental". A 0.3.1 release will be released to harden these latest features. If you want to use C# your best option at this time is to use Rexster with one of these two options:
https://github.com/dkuppitz/rexpro-client https://github.com/inthefabric/RexConnect