Stored Procedure AND/OR ORM for a BI web app

I am building a business intelligence web app in php 5 that display informations retrieved from a datawarehouse highly normalized (60+ tables in mysql).

We use MODx as our CMF to organize the code. So far the code is mainly procedura, each page is essentially composed of a bunch of sql query directly in the php code (Snippet as in the MODx terminology) and code to display the info in tables and graphically.

We are in the process of creating objects for our main components and put the sql queries there and use PDO. It is easy to do when the query map to a real object of the domain.

For more BI (aggregation with subqueries, join on 5+ tables) or search oriented query, I find it more difficult to see how to replace the dynamically created sql. For example, we have a search functionality in the web app with a lot of criteria. Depending on which criteria are selected, the php code add 开发者_运维问答or remove tables to join, subqueries and change the 'where' clause.

Do you think an ORM or Stored Proc could improve performance/quality of code in that context ? Is our model (60+ tables highly normalized) too complicated to be directly accessed from the web app and a kind of datamart (basically denormalized view of the data) would bring more benefits than ORM ?

This question is related to : stored-procedures-or-or-mappers

The bottleneck would surely be the level of normalization - if the option is available to you, adopting a more star-schema style DWH would greatly increase performance as it pre-prepares the data for consumption by your BI app.