I have lot of experience doing IT M&A from/to organizations that are completly have centralized and decentralized model. I think that that one factor to measure the dificutly of the project is the type of industry of the companies. I worked in several projects in industry (automotive and lifts) and are completly different. Automotive are more complex because the facilities need to follow with the production and providing goods to the customers, so any change in the systems has lot of impact. In the lifts industry is easyest because the production is not so ‘complex’ so the change can be done better.