Yeah, I agree with Todd. Grouping your hubs doesn't affect the Hubpages categories listed under your profile.
The main advantage for grouping your hubs is actually for yourself, not your viewers. I found it started getting helpful once I had about 20 or more hubs, that way if I wanted to go back to edit an old hub, there was no need to painstakingly hunt for it in a long list under 'my account'. Instead I could just narrow it down to a much shorter list by selecting the appropriate category and find it more quickly there. So all of that happens under 'my account', it doesn't affect anything on the profile page. Hope this helps.