The fuel use reduction is nice
Depends on the faction/ship though.
On Tugs logistics is spectacular (its totally worth it to buy lots of them to roll for a high quality one) also on high-fuel factions like Neutrino or Mayorate, some BRDY or low-tech vanilla ships, it can have a significant effect on your fleet upkeep costs.
I'd love to be able to see the % increases when buying the upgrade.
I'm not sure I'm happy with the % chance to apply though - its the kind of thing that promotes savescumming, which I'm never a fan of.
I'd rather the extra cost via % chance to fail just became flat extra cost and the chance was always 100.