ER to replace HDR in HA environment

We have been told to figure out how to replace our current HDR environment with an ER update-anywhere solution, in order to eliminate "outages" (planned or unplanned) with the DB server. Our environment: -- HP-UX 11.0 on identical HP RP7400 servers (8 cpu at 750 MHz, 16Gb memory) -- IDS 9.30.FC4XC -- servers are located hundreds of miles from each other -- high txn volume -- HA is *extremely* critical, no regular maintenance window -- schema changes occur 2-4 times per year -- for planned maintenance, we typically need two 5-10 minute outages to switch secondary to standard mode and move the client connections over -- client wants these outages, plus all unplanned outages, eliminated completely - figures that ER is the answer Has anyone else implemented ER in update-anywhere (aka, peer-to-peer) mode in a high-volume, extremely high-availability environment? If so, what should we watch out for, etc.? Comments? Recommendations? TIA, Paul Mosser sending to informix-list sending to informix-list