In fact it was easier when I went from not working in the cloud at all, to working in the cloud exclusively.
If it wasn't for the fact I am committed and can see the future benefits, I would have walked away after about 2 hours, and Google could of kept their 30 day free trial and I would keep my future monthly premiums.
But, reluctantly I persisted. Signing up for Google Apps for Business and purchasing a Domain was the easy part. Migrating my data was the impossible task.
Let's start with Contacts. Quite straight forward. Export my Work Group contacts, and import them to my new account. Good start even if it was a manual work around
Next up Calendar. Export my Work calendar and import it to my new account. Going well, but still a manual exercise.
Next, emails from . Export emails labeled Work. Oh wait. That feature doesn't exist. OK I'll enable POP access and have my inbox collected in to my new account. Oh no. It doesn't work like that (unless I ticked the wrong box). It collected every single email (all 1000) of them, including inbox, archived, and sent. But obviously the labels weren't synced. So now I have to try and run filters to separate personal emails from work emails. Not easy when Google doesn't seem to have "not" options ie "not from: xxx". Also filtering emails from a Contacts Group produced errors as the search string was too long. Needless to say, I pretty much ended up going through each email separately and labeling them, deleting non work emails asking the way.
Last up, (Drive, they really should change the name on the profile). Simples I thought. Share the folders and files and transfer ownership to my new account. Nope. It won't allow that because the custom domain is outside the Gmail domain. OK I'll download and upload the files. All well and good, but when you download Google files (ie gdocs, gsheets) they get converted to another format. You then upload them and can have them converted back to the Google formats. Well I know from experience formatting is lost this way. So in the end I had to download all non Google files only, and upload them to my new account. For the Google format files, I had to share them with the new account, make a copy in the new account and move those copies in to a folder owned by the new account, renaming then in the process to remove "Copy of". Very pain staking. In fact I've given up. One folder has a back catalogue of around 300 timesheets which stupidly I converted to Google format when I uploaded them originally to my Consumer Account. I'm not making copies and renaming and moving all 300. I'll just have to live with it for now and keep them in my personal account.
So my advice, if you are a consumer user be prepared to start afresh if you ever plan to move to a paid version. It really isn't worth the hassle trying to migrate data over!