Recently, I took part in a very interesting discussion on Linkedin about open source vs. closed source BI tools. It wasn't a general discussion on closed vs. open source. It was a discussion about Frankenstein BI (as closed source followers called the open source BI tools) and Big Businesses BI (term used by open source advocates to define closed source BI).
Dan Hofer, sales manager at an multinational company, said that few projects which integrated multiple systems into a unified system for reporting have used open source in the BI. „I look at open source like a Frankenstein. Lots of parts from different sources that don't integrate well. I'll take the stability of a closed source solution every day. At the end of the day, it's not about the technology - it's the ability to produce economically feasible business solutions”, said Hofer.
Instead, the majority of those who participated in the discussions said that open source allows a highest flexibility by giving the community the capability to modify and enhance the core platform.
Finally, it sounds like the general consensus is that open source and closed source are relatively equal as stability. The most important thing is to make sure your tool(s) match the project requirements and that they will play nicely with the other tools involved. And last but not least, be sure to find folks that are knowledgeable and can create end to end solutions.
Otherwise you will got a problem for your solution. Not the other, but you do BI for business based in business needs, not for sake of BI.