the approach you are taking is a very sensible one. In fact its how I got started in Navision.
By installing the ERP system for your self, you learn a lot in terms of what it can anc cant do. Going forward, its always a good sign for your clients that you use what you sell. So I suggest that you look at the products in these terms. The three products really do fit differnt market segments, and its not too hard to seperate them.
The strength of Great Plains is that is runs out of the box. It has never been strong on its modificability, but if it does what you want, or if there is an Add-On out there that does what you want, then its simple and easy to get going. A bit Plus/Minus of GP compared to AX and NAV, is that its quite rigind in its method of use. Accountants love it because it force the user to press th ebuttons inthe right order, and enter the numbers in the correct sequence. I.e. it allows the users to go into “brain off mode”, which is damn hard to do in Navision.
Navision is all about having it your way. the balance between getting down to deep programming, and getting a reasonable level of customization is about spot on.
An interesting side fact, back some years ago, Navision UK did a survey of its users, and had them fill in a number of questions. The most interesting response, was that to the question “what do you see as the major strength of Navision” was “its flexibility”. But in response tothe quesiton “what is the major problem you see with using Navision” the answer was “its flexibility”. The problem is that when people have flexibility and choice, they use it. Its very easy to make changes, so changes get made.
As to Axapta, its a great product, not too differnt to Navision, but it has one major advantage. And that is the marketing. This means that its much easier to sell big Axapta systems than big Navision systems.
In terms of what you need, Navision makes the most sense, but knowing the way things go, I think once you present the scenarios to your borad, they will go with Axapta, since it will look to be more profitable long term, and in fact it may be, I don’t know.
But if your long term goal is to get an ERP systme installed to run your business, and then be ready for the move to Green, then Navision would be a better choice.