The Dakar springs are the same design, just manufactured in Malaysia rather than in Australia.
I have the Original OME heavies that are 2.5" of lift.
I run extended shackles, which equates to about 4" in the rear and 3-3.5" in the front. The truck rides really nicely when I have it loaded down with gear. Empty it's pretty rough, but that's pretty common.
I need to replace one of the front spring packs. I can do either just the one with the Aussie made OME's, or I can get a pair of Dakar springs for the price of one spring pack (well, a little more).
I am really impressed with how long the original sprigns lasted (I am the second or third owner of the sprigns, and I have beat the S@#$ out of them).
I purchased the full Dakkar set up with greasable pins and shackles, and the OME nitro charger shocks about 3 months ago. I did the install in a day with the help of a buddy (SUA).
I would guess I've got about 1500 to 2000 miles on them now.
Major difference over the stock springs (69). Handles much better on and off road , smooths out the worst washboards, really improved the lean feeling when cornering, and they're great on the trail.
It's like driving a different rig IMO. I'm very happy with them. I'm glad I spent the money. I measured at the time of install - about 2.5" to 3.5" of lift from front to back. But my old springs were pretty flat. And I didn't use extended shackles. But I could easily run 33's now with no rubbing - in fact I have a set - but haven't put them on yet. I've still got too much tread left on the 31's.