NAV upgrade 2009 - 2015/2016

Hello,

We are planning to upgrade NAV. Currently we are on NAV 2009 GB classic client (We are only using classic client and not the RTC).
Now are in the need of upgrading to either 2015 or 2016 (decision still has to be made)

We have heavily customised NAV currently although some of the customised stuff is not been used.

We do understand that there is a massive change between 2009 and 2015 versions especially for us as we are only on classic client.

There is a discussion going on our end about having upgrade NAV or re-implement NAV. As we do not think we want everything to take with us to new NAV so new implementation is also making sense - then we can do the development of functionalities we need in the new version of NAV.

We are thinking about new implementation because at the minute we have a mess of customisations and if we upgrade and take with us all of that then new version will be a mess as well.

What would be the best practice for the above scenario? I presume NAV allows only data upgrade right without upgrading all the objects right?

Thanks,

Imran