You do not loss any data, but know this once you merge both profiles there is absolutely no way to revert it.
Secondly, when you merge all your previous chats history along with your GPTs move into the new workspace profile, and their sharing/access permission is set to be accessed by the members of your workspace.
So in-case you happen to share anything with public, or certain people who had link to your GPT, you need to update the sharing preference for each GPT again.
You don’t lose any data, only the ability to revert. Also, having two profiles comes with additional cost as the personal profile will still carry the “Plus” subscription, so there is no point in keeping both, but it’s your decision at the end of the day.