Hi Jun,
what IF ? - well, a few things must be mentioned here:
a) no real 'e-Commerce' (B2B or B2C) would have a 'migration path', as we both know the Release Notes are not extensive; so what SAP basically provides with NWDI can be easily discarded anyways;
b) no real 'patching' has happened on these technologies, and when it happens you can always do a full diff on both vanilla version files and see exactly what changed - and base your upcoming changes on that;
c) since having NWDI also does not guarantee compatibility (because SAP will break it most likely), I guess it's always win-win because you would end up with a much more adequate development environment;
Cheers,
D.