StudioPress Community Forums - Simple-Press forum vs vBulletin forum

I'm evaluating using either vBulletin or Simple Press forum plug-in My site is a content heavy site for teachers and parents and most of the forum discussions will center around general education questions and answers -- no support and no current plans to use the forum as a means to sell subscriptions. I'd appreciate any advice on either platform. I've outlined below what I've researched and concluded so far:

vBulletin

- uses a separate database and is a completely separate install. Can integrate with Wordpress but sounds pretty tricky.
- costs around $200
- Functionality includes forums AND calendars, events, polls, groups
- It appears that you have to use their separate Google XML sitemap module versus the XML Google Sitemap you may be using via a WP plug-in
- Good SEO including customizing meta tag titles, descriptions, etc.
- Flexible user permissions
- Every forum option you can think of
- Paid subscription options
- Can be skinned to mimic your site but since it's a separate install you're essentially replicating your site header, etc. and have to duplicate changes.
- Huge user base and very stable
- Lots of programmers familiar with the software in case help is needed with integration
- Positive comments on this StudioPress forum from what I've found
- Active forum

Simple-Press
- Integrates as a plug-in and uses the same registration system as Wordpress. I haven't installed it but assume that it adds tables/fields to the existing database rather than creating a new one.
- Free, though they do survive on donations to keep the engine running smoothly.
- I've read in a few places that it can be a bit slow. However, they've come out with a few new versions so perhaps that's been addressed.
- Good SEO and interestingly it integrates with the All in one SEO plug-in. Ability to change title, description, keywords, etc.
- Works with the Google XML Sitemaps plug-in
- Customizable to fit with the site look. It also appears that you can integrate while keeping your sidebar.
- Blog posts and forum topics can be linked. Hmm. Not sure how this works exactly but it sounds potentially interesting.
- Large user base and tested with WP 3.0
- Positive comments on the StudioPress forum
- Active forum

My pending conclusion:

The only real advantage I can see with vBulletin over SimplePress is the paid subscription option and possibly a little speed (if I'm right). Otherwise, Simple-Press is lower cost, appears to be stable, integrates well with WP, and works with the existing Google XML sitemap plug-in.

I'm interested in any comments. I'm sure there's some good points I'm missing and want to be sure to integrate the best solution on my site.

Thanks in advance!

Jerry