^^^ Some of the West Aussie dakar competitors/ADV inmates over the last couple of years have used them - Safariberg
PM/contact them and get some feedback...?
Like you (when I saw them originally) my first thought as to rally use, was the durability/abrasion resistence of the lightweight material, which looks akin to many of the lycra typ products used in cycling/triathlon etc. (which is the field/background - if am am not misstaken - that Sprint designs come from).
My interpretation (possibly incorrect) was that these lightweight summer "jackets" that they were possible not that much more resilient that a regular MX type jersey - in terms of durability/abrasion resistance - but they had the features of a jacket, with zips, vents, pockets and facility for neckbrace etc.
A bit like a yellow "tour de france" pullover... one thing, being light and the possibility to have them printed up/designed in the sponsors colours/logo easily, that possibly you would have a few of them in the gear bag... as opposed to just one relatively expensive heavy duty jacket?
I like the designs and look of the Sprit stuff... only the Kenny jackets of Despres/Coma etc. look as sleek, form fitting and light/functional of those jackets I have seen the last couple seasons.