I'd like some advice and commentary on using the Confluence / Theme Builder combination for hosting a public web site. Obviously Adaptavist is doing this, using Theme Builder and Community Bubbles.

I'm strongly considering Confluence/Theme builder for my own company's web site, replacing a php/drupal based web site, for the following reasons:

1. I've been working with Confluence for a few years now, mostly inside of corporate firewalls with a user community that was (usually) well intentioned and authenticated. I like the product and Theme Builder / Bubbles as well.
2. I have the need to create product manuals that live both online and in print. Space export to PDF handles this reasonably well. Doing it from Drupal is a mess of plugins.
3. My Drupal based site has been hacked a few too many times. Keeping up on the security patches is a big job. Lots of patches, regularly, and more for the sundry modules (plugins, if you like), that add the functionality I like. Yes, Confluence gets security warnings now and then, but they seem few by comparison. Maintenance seems easier.
4. Customization with Confluence / Theme builder seems easier. If I were a php/Drupal expert, I'd probably be better at doing what I want on the site, but I've more experience with Confluence / TB.
5. I'm the only tech guy in a 4 man company, and I just don't need another headache. I know Java / J2EE well, and the architecture is more appealing than the (s)cryptic nature of php/Drupal. I don't really want to be a php/Drupal expert.
6. Hosted solutions for Confluence are reasonably priced for a small number of users.

A few things concern me about using Confluence / Theme Builder for my site:

1. I'll be allowing anonymous access for the public parts of the site, but I will definitely have confidential material that I don't want to share publicly. It would be very bad for my company if this information was released. Is my system going to be secure?
2. To me, many public Builder sites seem to load slowly. This seems to be much less the case in later versions of Builder.
3. Bubbles is great for doing a forum (which I would like to do for my customers), but per user pricing for Confluence makes this an expensive solution for me. I've a few thousand customers, but only 4 employees. (OK, I'm whining a bit here.. but forum users are a bit different in my mind than general contributors)
4. I've really no idea how high the load will be for the public part of my site. My public web site today doesn't get too many page hits, as we operate in a very specialized industry.

While Atlassian gives some advice in the Confluence documentation on creating an Internet facing system, I wonder if there is more "best practice" or other things I should consider before making the switch.

What else should have me concerned? Am I missing anything here? Is there some other solution or combination I should be considering?

Thanks to any and all for the consideration. And Adaptavist folks.. nice job on the new site.