Creating new version of existing site: advice please?

Hi

I am considering creating a completely new version of an existing site (possibly offline using desktop server) but I would like to use Upfront builder and base the whole thing around Marketpress.

I have run into big issues trying to overwrite existing databases and files using the Duplicator in the past so I'd like to explore doing this some other way.

Is there a role for Snapshot in this process (other than as a way of restoring should I break the site)?

An argument might be made to retain the existing site and edit it live. The site is old and there have been numerous changes I feel it might be time to archive the old data and get it clean but perhaps this is more trouble than it's worth.

As it's a commercial site I cannot afford for it to be offline for any great length of time.

I appreciate your help. Thanks.

Paul