I use w3 Total cache.. I use the CDN, the Database Cache, and the Browser Cache… I do not use the object cache as it completely screws things up… the page cache will also completely screw your site up… I do not use the minify cache in W3, but I do use wp-minify for javascript and css compression….
I had problems with WP Super-cache, but I don’t remember what they were and they were obviously related to the page cache though…
What I really need is a way to CDN the avatars… this would be a huge help, but so far no one has come up with a good way to do it other than @apeatling on the BP-Demo site, but none of us know how he did it yet… 
It’s pretty easy to do that @Pisanojm! I’ll write about it on BP-Tricks today or Monday!
I use WP Super-Cache and WP Minify just fine. I would use W3TC but I use multisite functions like switch_to_blog alot – i mean alot – and they just aren’t supported by the plugin and it won’t be until WP3.2 that switch_to_blog is compatible. Once it is I will go back to W3TC, – – maybe — ever since I’ve been waiting for it to work I’ve been getting Super-cache/WPminify and a few other tricks to get my sites almost as fast or just as fast as I had them with W3TC. I’m currently testing out FV Gravatar plugin for gravatars https://wordpress.org/extend/plugins/fv-gravatar-cache and I’m going to do CDN next since WPSupercache does have a CDN feature. Overall, I think Super-cache has been more Multisite friendly and more user friendly as well.
@bowromir That would be incredible!
@bowromir ..very excited to see what you come up with for a cdn for avatars today!
@Pisanojm: writing it now.. as promised!
It took a while.. but this should be pretty much all you need to know about setting up a CDN with MaxCDN/W3 Total Cache in combination with BuddyPress. The good parts for the people who already have a CDN running can be found at the end.. Hope it’s useful!
http://bp-tricks.com/featured/the-perfect-cdn-setup-for-buddypress-using-maxcdn-and-w3-total-cache/
This is very well done, but there are still issues with what you have described and getting it to work with personal/group avatars… I detailed on your site…
Reading up on it now, but the problem does not occur on my setup(s). It does seem to be a issue popping up more (reading the thread you pointed me to) but I have not experienced the issue.
Bowe… carrying over this conversation here… It does seem indeed that the issue is because of the older Amazon S3 technology… I’ve switched to MAX CDN mirroring and the problem I’ve bean having for over 7 months with this virtually looks like it has disappeared! I will report back in a few days to a week on my progress. Best!
I tried Bowe’s method using W3 Total cache and Rackspace CDN (CloudFiles) for a 3 dedicated servers setup – 1 db, 2 frontend.
It failed at the crop avatar step. Everything else was fine.
We had to use NFS instead to sync avatars across the frontend servers – ugh.
Still using W3 Total cache for CDN for other files.
@Pisanojm: did MaxCDN allow use of CDN for avatars for you ?
