I'm working with a web company that's approaching a point where it will likely need re-think the product as a V2 - due to outgrowing some of its V1 foundations and principles that have been built into virtually everything, from the data model to the user interfaces. For various reasons, this evolution might involve a migration from CakePHP (with which the V1 has been built) to Symfony or Zend.
I would like to ask for some experienced views on how people might have managed a transition like this for a website that has significant traffic and generates revenue. I don't want to open up a discussion on the pro's & con's of different PHP frameworks, or why this migration might be needed. Rather, I would be very interested in hearing whether there are some practical alternatives to essentially building a V2 from scratch alongside the V1 for a couple of months - and locking up precious coding time for the duration of this intense period. An example of such an alternative might be migrating an app in parts over a longer period of time.
I'd be grateful for any views from people who might have managed or been involved in such transitions.
Thanks in advance.