True, but it can be hard to do a sneak and peek when travelling at 60-100mph.
Also, it is worth remembering that we’re looking at a worst case scenario for a VTOL, surprised at short range by an infantry platoon.
For the purpose of the debate, avoiding being hit has been and gone, the question now is what armour gives us the best chance of surviving the turn until we can bug out.
Challenger
Flying VTOL correctly:
"ooh! surprise!!" (mass of fire shoots up around without hitting)
Flying VTOL incorrectly:
"Ooh! surprise!" Boom, because they've been lingering and creeping along like a tracked assault tank thinking they're being stealthy at urbanmech-like speeds.
or...
"Oh shit, sidesli-" Boom, because you were flanking at 1 AGL to try to hide behind light woods and have become one with the terrain.
Trying to treat a VTOL like a 'mech is one of the main mistakes players make in this game, and it's encouraged by ideas like "Let's make the rotor into a gigantic fire-shield instead of the chief vulnerability of the vehicle!!"
Fact is, yes, it's tough...but you're using a VTOL, not a hovertank, Wheeled Tank, Track, or 'mech. There are going to be tradeoffs and you need to run it accordingly. one of the things about running VTOLs correctly, is you
do not stick around in one spot. You need to have your path plotted during the fire phase of the last round, with options thought out in advance to account for the other guy's objectives and equipment to the best of your knowledge. This means you're sweeping the whole map, as much area as you can, in a pattern or patterns, but not lingering-because if you're lingering, you're doing it wrong.
a no-guns ferret with a mast-mount is cheap enough to bring TWO (or more), if you need to surveil a specific path or terrain feature, you run alternates. Choppers are not 'stealthy'. if you want stealthy, you run a stealthy tank, or purifiers, or stealth-armored 'mech.
or you plot your movement to use terrain to screen, which if you don't want to become one with the terrain, means a high cruise speed and afterthought armor.
the exception does exist, of course. Get you a Donar with Ferro-Lam, because someone thought that it was a good idea to make a vehicle with a 50 point damage buffer that ignores lbx and lrm impacts while it ignores terrain restrictions and carries more payload than an equivalent weight 'mech, and someone else thought inserting it into the game was a good idea.