Crabatron has high health and spacing (40 spaces) while Ichi has lower health and lower spacing (20 spaces).
2 Ichis = 1 Crabatron in both damge, spacing, and health. So when you produce Crabatrons instead of Ichi, there will be fewer Crabatrons.
When it comes to taking down splash damage towers (e.g. Laser/Cannon Towers), Crabatron would take them down much more easily than Ichis would. Crabatron's weaknesses are high damage towers like Teslas and Snipers. When attacking someone using Crabatrons, nuke the Teslas instead of Lasers. Beware, at higher levels the Ichi has more health per housing than Crabatron. But, at level 6, Crabatron is faster than Ichi by 0.3 kph.
Use Crabatron along with Project X to do massive damage to towers. Send Crabatron in first to soak up firepower, then send Project X to do damage to the towers. Preferably, the monsters would be slightly spread out, as splash towers still do significant damage to Crabatrons. Ideally, as Crabatrons are killed, other Crabatrons would replace the dead ones by passing in front of Project Xs. You can also send a Zafreeti after flinging in the Crabatrons and Project X to heal the monsters.
Crabatron activates Heavy Traps and can be easily killed by them, so do not fling all your Crabatrons in one shot.