Well,

All data warehouse products provide flexibility and good tools to build strategic reports focus on KPI. All of them also provide easy to use tools to display and organize analytic information..... I guess that the decision about what product will be chosen will be based on how difficult is to pull (and keep updated) the data from the transactional systems behind. In other words, if you are running SAP to manage a big part of your day to day transactional system, go for BW / BI.
In SAP BW / BI, you have a large group of extractors and predefined processes that enable you to pull the data from the SAP systems into multidimentional indexed data providers. Once the data is there, you could easily develop your own queries and reports, organizing them in almost whatever way you want and building almost any possible KPI you want. You cloud display and manipulate these queries and reports using almost any single PC product you want......
Now, if your data sources are not base on SAP ...... mmmmm ...... Well, you have to build your own data extractors . You also have to build your own data warehouse targets (data providers) and your own mapping processes. You will be dealing with normalization and database definition concepts. Being technically feasible, probably is not the best path.
If you have an hybrid situation (some SAP systems and some NO SAP system), you will evaluate how many strategic data sources you have in each size and take a decision base on that.

I hope this helps......

Luis E. Lavieri
City of Vancouver, BC