As best I can figure them, the new odds for 5th edition Vyper damage results with and without holofields are as follows:
Glancing hit with holos: 75% shaken, 14% weap dest, 8% immob, 3% destroyed
Glancing hit without holos: 50% shaken, 17% weap dest, 17% immob, 17% destroyed/explodes
Penetrating hit with holos: 31% shaken, 25% weap dest, 19% immob, 25% destroyed/explodes
Penetrating hit without holos: 17% shaken, 17% weap dest, 17% immob, 50% destroyed/explodes
This does not take into account cover saves from either being obscured or being a fast skimmer moving over 12”. With armor 10, I would guess most of the hits on Vypers will be penetrating ones, so basically holofields are keeping you alive twice as long as without. Any pesky bolter shots that do glance your vypers have a much lower chance of bringing them down too.