I think it's good to have a website.
If you put your all your eggs in one basket and something goes wrong you're up the creek without a paddle.
Remember when AW was down for a whole day on 28/12 last year, many were panicking and lost potential business (myself included).
AW is good if you want to dip your toes in without commitment, expense and hassle.
For me, having my own website allows me to express myself fully and the only limit to that expression is myself. I can also promote myself to a wider audience with a website. I like AW but find I'm stifled as can only express myself within their limits.
With my own blog, twitter, etc I don't have to worry about things being removed, edited, etc. Something that AW like to do depending on their mood. LOL.
I still get the majority of my bookings via AW but my sites still fairly new. Bookings are now trickling in from other avenues, including twitter
And it's true what the ladies above have said. Clients will read your blogs and site, find out more about you than the odd random blog on AW and one profile page. Does tend to make for better bookings, clients and experiences.
Why limit yourself just to AW? When you can have the best of both worlds.
Just my rambling thoughts on a Sunday