Where best to install EFGEN Interface

Hello:  I'm trying to figure out where best to install the new EFGEN interface.  Traditionally, we've used PiBaGen on our PI Server.  Now, we have PI2012 and AF2012 (w/ SQL Server Std.) on one box with an interface node in our North building and an interface node in our South building.  I'd consider this a "small" application with 4000 tags with snapshot and archive rates less than 4000 events/sec.  I anticipate ~1000 elements and 12000 events/month.  I've read you should put EFGEN on an interface node, but I get confused when we have two interface nodes.  Should I install an EFGEN instance, per node?  Can I put it on the PI Server node?  What are the loading considerations?

Thanks!