I know what you're talking about, pandask. My blog started out on WP.com and was then migrated to its own site.
For any of you that have never been WP-hosted, there is a great sense of community there and "inside" support. As someone who posted regularly in their support forums, I gained literally hundreds of individual visitors each month coming to my site from the forum links. Also, they have "best of" and "top performing" lists of blogs linked from the main dashboard admin panel. You can get some idea of this on the wordpress.com home page.
When others have asked me whether they should move from WP hosting to paid hosting, I always ask them what it is they're trying to gain that WP doesn't offer. In my case, I needed advertising and the ability to directly control my theme, overall CSS, and even core functionality. If you can't name something very specific that you need to do with your site that can't be done there, then there's probably not a good reason to move.
DISADVANTAGES
- You'll confuse your existing readers and probably lose some of them.
- You'll lose any existing standings or PageRank you may have already built up.
- You'll lose any existing outside links to your site.
- When something breaks or gets messed up, there's only you to fix it or pay someone else to.
- You'll no longer be included in any of the wordpress.com listings of "best of" or "best performing" blogs or other categories specific to that community.
- You will definitely miss the natural sense of community and interconnectedness that exists on the WP-hosted blogs.
ADVANTAGES
- Direct control over any and every aspect of your site.
- You can put as much or as little advertising as you want.
- You can use any JavaScript or piece of code that happens to catch your fancy.
- You can use ANY theme or plugin out there.
- You can tweak any piece of code or formatting till it's just the way you want it.
That's just a short list, but you get the idea. Self-hosting is not right for everyone any more than WP-hosting is. The decision comes down to weighing the advantages against the disadvantages.
Again, let me repeat, if you can't name something very specific that you need to do with your site that can't be done there, then there's probably not a good reason to move.