The answer depends on 'where you're at with where you are.'
I'm no expert, but here's my 2 cents.
If you are in a big category and ranking high (in the good sense: low, low numbers) way to go you. Congrats! Stay right there.
If you are in a big category and ranking bad, you need to narrow your focus and get the hell out of there. Find a smaller pool so you can come up for air.
The bonus is you have two dashboard categories to play with - and options to drill deeper within each of them. Don't forget, some categories can also be accessed via your keyword choices.
AND the even bigger bonus is you can simply ask the mighty Zon to add you to other categories. I'm pretty sure you can have a maximum of ten categories in total.
Of course, you'll no longer rank for any categories you leave, so be clear of your objectives. If you want more visibility, choose a smaller/less competitive pool. If you're smashing your current cats and looking for growth, time to dip your toes in a bigger pool.
I don't know of any downsides to changing, but choose carefully and make them relevant to the audience or you'll create your own downside in the form of poor customer reviews. Good luck. May the force be with you!