Hi Jester
I had a full leather retrim in my Cali.
having experienced perforated leather seats with a stitched seat back and pad, on another two vehicles both had heated seats, my experience with those vehicle was based over 100,000 miles and was a very good experience.
The combination of Perforations of pattern stitching did not pick up any discernible additional dirt etc, they were easy to clean normally and they allowed the heated seats to heat up as intended (without the extended delay that can be associated with leather) the combination of perforation & stitching pattern on the face ensure the ”stick” feeling you can get on bare skin / leather is negated.
the perforations coupled with stitching pattern ensure the seats regulate the temperature better (from your body) they also prevents bagging that can occur on flat leather panels.
Similarly I have leather sofas at home, where the heat and Stick is noticeable
I opted for a full leather (premium real leather) with perforated and pattern stitched seat pads.
my experience to date is very very good.
I wear shorts most of the year, I have had no issues with sticking to the leather seats in my Van.
conversely I have another car, it has factory leather seats, it does not have perforated or stitched seat pads, the seat pad and back are large flat panels, the same cannot be said for that car, the leather in that car generally generate more heat from purely sitting on them and yes you do get a certain amount of stick On bare skin, the seats show signs of bagging To the seat pad.
in the end the decision to go for covers or a re-trim be that leather or any other material or combination is a personal choice, but there are mitigating factors to be considered for each potential option.
Each has its own merits and potential issues, only you can decide what the perceived benefits may be And what is right for your intended use.
I post this to purely highlight that one of the reasons you give for not having leather on the seat pad / back may not be an issue if you choose certain design options.
I hope this helps give a balanced opinion and possibility offers another potential option to consider.
edit , fully air bag compliant and labeled appropriately on each seat (as are the iso fix points ) photo two shows the air bag compliant tags on the upper left as viewed in the photo, if you look closely at the rear bench you can see the iso fix tags, exact where they are on the factory seat covers
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