Thanks for that info Monkfish...
websites are a mixture of flat file, html & various CMS`s (wordpress etc)
So whilst some of them will be straight forward, some wont....getting backups of all sites will also be easy.
Ive already tried a couple of test imports using wget, but that didn't work too well, files weren't put in correct place, So I`ll need to read up a bit on that.
Then when I manually ftp`d file to correct location, I couldn't really test site, cpanel gives you a temporary url xxx.xxx.xxx.xxx/~username where you can check site, but I couldnt do that with ispconfig (Ive probably missed something)
Ive already set TTL low on DNS, so that bit is done.
ISPConfig, does look to be the best of the free panels.. even better than some of the paid ones, but it doesn't make it easy to move established setups into it. Not a complaint, just an observation
I`ll persevere for now & continue with my testing & evaluation.