I do not want to belittle your personal experience, but two companies make no convincing picture, IMHO. I am working daily as a developer with ERP systems. Once

I do not want to belittle your personal experience, but two companies make no convincing picture, IMHO. I am working daily as a developer with ERP systems. Once you get used to the idiosyncrasy they are usually no longer slow or hard to use (unless the implementation partner has really messed up - which happens). Open source ERP can neither cover the functional range of main ERP systems like Oracle's or SAP's, nor can you expect the same level of domain knowledge being applied to it in development (with a small fraction of the developers the large ones have, lacking the specialization at the large vendors), nor do at least I know of success stories in that regard with Fortune 500 companies, as their main, driving ERP system.