Have a limited experience with 3M installed in my colleagues car and the next day I got these installed I compared the result and frankly I could not tell the difference. Maybe they offer better rejection and for more time as duration of heat rejection is limited for these tints. 8 hours in case of Solar screen.
Heres how I would review them.
My daily travelling is east to west in the afternoon and the sun shines through the windshield through out my journey of around 20 kms.
Before these tints AC had to be atleast 50% speed and my lower body which had continuous exposure to sun used to burn and I could feel my clothes getting hot and hotter.
Now AC runs good at 25% speed and the body does not burn.
It feels warm but not hot or burning.