Are NiFe cells worthwhile for a small solar PV Battery setup?

NiFe cells (Edison Cells) are very old battery technology first patented by Edison around 100+ years ago and were used for the first electric vehicles (competitive with early petrol internal combustion engined vehicles). The main advantage of NiFe cells over Lead acid are that they are less toxic (disposal issues with their much shorter useful lifetimes of lead acid), have useful lifetimes approaching 30-50 years, are extremely robust and have slightly higher energy density and can be stored completely discharged unlike Lead-acid cells. Downsides are higher self discharge rates (not really critical for solar PV) and have less efficient charge and disharge cycles. Finding suppliers appears to be extremely difficult as they appear to be only available from Russian or Chinese manufacturers/suppliers.

http://www.armyradio.co.uk/arsc/customer/product.php?productid=1481&cat=87&page=1