You have to invest more time in getting the low-level design right because you intend to reuse your objects. There is more to training than simply sending a couple of programmers on a course. Even after an excellent course it will take nine months for your personnel are back up to something like full productivity. Before you start you should consider whether the move is realistic for your business. They are the ones that are hit hard by changes outside their control.
Tax laws change, currency regulations and currencies change and so on.
They also have to work to tight deadlines. You cannot ask your tax inspector to wait another year till you get your software written and debugged. Well you can, but you know what the response will be. Application Developers Guide to Object-Orientation . The author claims that the book is aimed at designers, programmers, and testers.