This is good because the ERP is a completely different animal than a data warehouse. The ERP is meant to perform transactional activities and the data warehouse/BI system is meant to be used with historical data for analysis. So, is your problem with the warehouse or the ERP?
Agreed. Look into what the business needs are first before considering expanding ERP, especially away from configuration into customization. Once you go down that road, it's hard to come back and you're screwed at every upgrade. Look into ways to integrate your ERP with other systems either COTS or home-grown and use each system for their specific purposes. Integrate them via a Web service so that the updates to each system don't significantly impact your other systems versus an interface. Most open systems have APIs that work sufficiently. If you have a closed system to integrate, you might have to use an interface, but make it as simple as possible. Also consider your data. Keep your financial and hr data in your ERP where it belongs and keep your other system with their 'owned' data so you don't replicate too much data back and forth. It sounds like you're looking more into a BI dashboard or some BI tools required which there are tons of vendors out there with COTS systems. Also, if you're looking to perform more analysis, you'll need to look into a data mart or data warehouse. This way, it takes all the things that are being done in spreadsheets and moves them to a server in which everyone can use and share. You'll also need to set parameters with some sort of business analyst to make sure you're doing it right. Nothing is better than getting a pivot table where the hypothesis is based upon the wrong theory. It takes lots of time and energy to determine what makes the best sense and it's not all IT/system specific. You still need to consider the people accessing your system and your processes - both present and future. Figure your business case first, then gather requirements because you'll probably find it's not the ERP which is meant to be transactional, but everyone is using the ERP to do things the ERP is not designed to do.