I agree that it depends on what you want to do with it. We have a main site and our mirror on Tapastic. We put most of our efforts for advertising,, blogging, etc into our main site and we focus on different things here. I have noticed that your audience will tend to stay where you find them, so people who follow the main site tend to go there and people on Tapastic tend to stay here.
If you are going to focus more of your efforts here you probably don't need to have a website, but I still would recommend keeping one in case you would change your mind down the road, and as someone mentioned, your domain name could be taken then.
If you do your own site, I agree that Wordpress/Comicpress is a good way to go. We use them on our main site and we have had very few problems.