Don't know if this is still an issue, but I seem to recall a few years when these pop up springs were all the rage, that longterm they caused some damage to the area where the strut meets the tailgate bending and in some cases tearing the sheet steel.Don't know if these issues have been sorted on later versions of the mod though ?
I bought and fitted the struts from Alex at vw Retrofit around 12 months ago,a very easy install-just remember to prop your tailgate.Touch wood,had no issues,yes the tailgate is harder to close,but it’s only slightly harder.I don’t think they are powerful enough to tear sheet steel or bend the tailgate.The only thing I’m paranoid about is parking too close to a wall and catching the tailgate as it opens.A very handy,relatively cheap mod in my opinion.