I’ve tried and left a number of hosting companies (BlueHost, Netfirms, GoDaddy, A Small Orange were among the worst experiences). I haven’t tried zippykid, but the two I mention below are the ones I’ve settled in with for the long haul.
1) My recommendation for those looking for high-value, high-performance hosting without a big budget: The Temple Host. Their $15/mo Business Plan should take care of your 2,000+ member cbox community for a good while and they’ll work with you if you start to outgrow that account and need to upgrade to a VPS (which is still well under $400/yr).
W3 Total Cache is exactly the right plugin to use. Temple Host has memory-enabled caching so when W3 Total Cache is enabled on your BuddyPress install it works wonders. It doesn’t do that on crapDaddy because of how they have their servers configured.
A group of volunteers and I are setting up a wordpress multisite install with buddypress/cbox and eventually hoping to get it to talk to an install of localwiki. The Temple Host support is always super helpful. There’s not a lot of spit and polish on their website or hosting panel, but I’m convinced they put a lot of attention on their servers because they perform great.
2) For those with at least $99/mo to burn wanting robust hosting with cool features like built-in, easy-to-use backup/restore and deploy with git, WP Engine is the only other host that I like. Their customer support is very good. The link I’ve included is an affiliate link. I help host nonprofit sites like breadforthecity.org and mobilize.org. I don’t make any profit.
If you’re reading this and already have a WP Engine account, join their affiliate program – it can make the cost of their hosting a tad bit cheaper.
Hope you or someone else finds this helpful. Good luck!