We got hand on brand new Dell Rack UPS 5600W. It comes with EBM (Extended battery module), NMC (Network managament card) and Environment probe (Temperature and humidity). It has some nice integration with VMware vCenter for automatic host/guest shutdown. This automation is included in the price.
It has run time of impressive 49 minutes at half load. For our current configuration (about 1000W) it will last for about 5 hours without external power. Also, it needs so much power, that its Power Cord must be hardwired.
Some images below.