Personally, I've had involvement with two ERP installations, both using SAP. My role was adjunct in that I developed some integration routines between various modules, along with some data conversion utilities and the like. Both of these projects had huge cost and time overruns, and I can assure you, that it was not a management problem, either from lack of vision, direction, involvement, or input. In fact it was the exact opposite. The inflexibility in the software hindered management's ability to fully realize the business model that was at the heart of the success in building these two multi-million dollar companies.
Secondly, as a result of a corporate merger, our company and an SAP company became one and direct face to face conversations with some of the SAP consultants also contributed to, and reinforced, my position. We also had some JDE consultants on the payroll, and off the record, they too echoed the same sentiments, and if you wish to write that off as heresay (which is really is), I certainly couldn't blame you or disagree with that.
That being said, I am well aware of the fact that some ERP installations have gone fairly smoothly. The over-riding parameter seems to be in how closely the existing business model matches up with the model being dictated by the ERP system. The closer the two are at the start, the higher the probability of success, and perhaps your case, as evidenced by the fact that your changes were minor, lends some credence to that.
I think you illustrate what I feel is at the crux of the issue by your statement -- "I think where you find companies getting into trouble and losing tons of money is when they try to fit the ERP package to their business, customizing it to no end." Why on earth would you buy a piece of software that you would not try to fit into your business? The alternative is the fit the business into the ERP package, because, ultimately, the two have to be in synch. But isn't that backwards? Unfortunately, the EPR systems generally do not have the flexibility to be easily adapted to the existing business model. IMHO, the software should not dictate the business model.
Good Luck
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As a circle of light increases so does the circumference of darkness around it. - Albert Einstein