RDBMS vs NoSQL
Try not to throw valuable data away, it does not matter if you store it in RDBMS or NoSQL, if you failed to store it you will always fail to find it with a search.
A number of RDBMS allow you to store semi-structured data (think JSON or XML), just like their NoSQL brethren, this allows you to manage structured and semi structured data in the same system, allows you to keep to ACID and all those things that are important. Just don't mess (update/delete entries) with the JSON/XML structures too much as this could be a big DB hit.
Do indexing, yes even in NoSQL, saves your big HBASE batch jobs from taking far too long.
Most importantly understand your data and its relationships, if you don't know that a field exists because your developers are a bit vague, then you will never be able to search on it, unless it is in a RDMBS of course, where you will have that helpful schema to fall back upon.