Hey Bob... good luck with your pilot. And go Huskies!!! I grew up in South Windsor and will forever be a UConn fan. :-)
We have a couple JIVE instances hosted at National Instruments today (internal and external community). In both cases we use a 2 node cluster which has load balancing. However, as it stands we can handle all traffic on a single node - at least for a small period of time. This has been very helpful as we can remove one server from cluster for maintenance / troubleshooting / restarts giving minimal user disruption. At DB level... we are in-process of migrating to Oracle RAC... which gives us some flexibility / redundance at DB layer.
One of our instances is on JIVE 5 and there are several new services running for this version (as compared to 4.5). Today we are running cache, activity, and doc conversion services on separate VMs. Exception - We have coupled cache and doc conversion on same server. Had to play with sizing and doc conversion configs to get them to play nice on same box.