I like their JTAG enable pin, so you don't have to loose valuable pins for JTAG - but they are narrow Vcc operation, and only promise < 100uA, and Xilinx do not have them on the on-line store, and are sparse elsewhere, so have that NFND look about them....
How long is your product lifetime ?
Yes, normally it is simply a SR latch, with some logic to catch S=R=H. When running, S,R cross their thresholds only briefly, to trigger the other phase.
-jg