Hadoop is the problem, MapReduce is not the problem. Having used both Hadoop and Disco, I can say that Disco is by far a net positive on all projects I used it on. And the overhead to coding it in Disco vs single node is about an extra 30 minutes. You can start with working single node and go multinode w/o much effort.
Hadoop on the other hand is a huge, massive pain in the ass. And I am a Hadoop consultant. I recommend that most customers NOT use it.