Micafilm is no longer made but is/was 25gsm wheras Ultracote/Oracover/Profilm Lite is 36gsm with adhesive. Having used both I’d say that ‘Lite’ has better puncture reistance but more importantly is non-porous. Early Micafilm was fine but the later stuff (I have quite a few rolls of it !) was porous to fuel and water so pretty useless.
I used to use Micafilm but now use the ‘Lite’ on the underside of all my F1A/F1Hs.
There is also a version of ‘Lite’ and the heavier film that has no adhesive on it which saves on weight but getting a good adhesive to stick the stuff is difficulat apparently.