I think you would not use Theano in an end-user product. It's made for developers to run on developer machines. It's very fragile. It has a very long start-up time, might be in the order of several minutes at the first start.

Maybe it would work good enough in a service backend. But even there it would not scale that well. For example, it doesn't support multi-threading (running a theano.function from multiple threads at the same time).