... Any more details on the springs?
Here is the summary about these Leaf Springs (info I got from the supplier):
They can be fabricated as per ones suspension needs
soft: for regular road usage -- a replacement for the stock leaf setup
stiff: this is for folks who go rallying etc.
The 'soft' ones are available of the shelf, where as the 'stiff' ones have a lead time of 2 months.
They don't advise to put these in the front, as for some reason there seems to be a wobble in few vehicles where they have put it. They want to investigate this and fully test it out before recommending it for the front of the vehicle. They don't want to recommend/sell for the front just for the sake of it.
However, if someone insists they will fabricate as per requirement
These have been tested extensively and for past 4 years these are in use in various vehicles. Absolutely NO complaint so far. He even mentioned that many Ford Endeavors get this setup done.
It has enough flex & even somehat similar to wringing of clothes type of flex is possible and the setup won't fail/break
In off-road, even if hits a rock etc, it will not break/fail. At most, if it is hit by a razor sharp thing(maybe a razor sharp rock/edge), it might get bruised/defect -- but that also he said should not happen as per his experience. Even in that case he mentioned free replacement.
Here is a video that shows some more details about these leaf springs
http://message2.myvideowebstream.com/view/?id=TDHE9679BS4UVVCHWGKK