Here’s some answers and personal thoughts.
-Customising BW – custom cubes and loaders :
Custom cubes are very easy to create and almost always needed for tailored business needs. We used the standard LIS loaders with some modifications for master data.
-Administration workload post go live
If you get the structures up right, almost no administration is needed. You need to watch the data loads closely until it is stable, and from that point it is fairly simple basis. I practically run the entire BW thing myself. (only 50 or so users in LO, CO-PA, FI-AR used in reporting)
-Changing data cubes post go live and reloading data
Especially in LO, refreshing data from R3 without stopping data entry is tricky. Other than that, data load and reconstruction is fairly easy. Changing the cubes/data sources can be done after go-live but can cause some downtime for reloading data.
And anything on the business experience – ie did the business get the benefits it expected to get?
Definitely. After seeing BW capabilities, people flooded us with new ideas and development opportunities. It is extremely useful in consolidating data from a number of sources.