True to form, with the first sites under migration, the first lot of improvements were visible, from both a usability and front-end aesthetic point of view.
These have been continuous throughout the week and we are in a fortunate position that, because we have built this in-house from the ground, up, and not based it on any existing framework, we are able to quickly react (not the framework/library) and make any improvements immediately.
Another stumbling block was how to create the version 3 site without affecting the current site, whilst still utilising the same paths and data and have them running simultaneously waiting for the final switchover. Again, easily overcome, but did require some tinkering with the new Admin Area, the Front End and the API.
We are now at the end of the week, and things are really coming together in terms of what is required for a migration. It has been important for me, that I have handled the migrations personally, it has allowed for this 'real-world' understanding mentioned previously.
Although the first migrations have not been completed, this is due to the final pieces of functionality to be put into place... *cough* search *cough*, as well as some final layout tweaking based on selections.
We are getting there and once a more solid migration method is in place we will be moving more and more sites over.