The Crab has no true long range capabilities, but a pair of LLas come into play at 20". Even at walking speed, the CRB-20 will start building up heat almost immediately; after five turns of firing both LLas, the mech's speed will be compromised from overheating. But this mech is built with a substantial number of heat sinks, and it takes 12 full turns of firing all possible weapons before the Crab reaches the redline on the heat scale.
Baseline ACD is a mediocre 99.78 points over 12 turns. Pushing the heat envelope at shorter ranges increases damage to 105.25 points - not spectacular, though the optimized damage curve is fairly linear and increases evenly as the CRB-20 closes. Running overly hot drops damage output by only 20% under the baseline run, which underscores the heat tolerance of the Crab. Everything considered though, despite two Large Lasers and a high number of heat sinks, the Crab is more offensively equivalent to a Raven, and outgunned by other 50 ton mechs such as the CN9-A Centurion.
For a 50 ton mech, the Crab is extremely durable. Enemies need to slag through the entirety of the CRB-20's torso or knock out the reactor with a few well-placed shots before the Crab stops functioning. It packs a respectable 9.0 tons of standard armor, with decent armor distribution. The legs are slightly over-armored, keeping the Crab mobile for longer - but armor is slightly under target across the torso sections.
With a top speed of 86.4 kph and no jump jets, the Crab is average speed for most medium mechs. However, it is able to claim that +3 target modifier when moving at full speed (with a little room to spare for turning or negotiating difficult terrain) which is a huge contributor to it's ability to outlast the competition. It also affords the Crab the luxury of taking on a small level of heat to increase damage output, but still be capable of maintaining a respectable rate of speed.
The CRB-20 Crab can deal out a decent amount of sustained damage at close range without overheating, as long as it alternates firing one or both LLas. But the real value of the CRB-20 is in its sheer survivability. It can stick in with some of the biggest mechs and take a beating before going down, without worrying about ammunition or minimum ranges; the closer the Crab gets, the more average damage it can inflict. Heat is the Crab's worst enemy, but a skilled pilot should have no problem managing the scale.
At maximum speed, the Crab can fire both LLas for two consecutive rounds without any adverse heat effects; firing a single LLas in the third round will wipe out any excess heat. This 2-2-1 firing pattern can deliver up to 40 damage over three rounds while maintaining a +3 target modifier, making the CRB-20 a frustratingly tough opponent, especially because it requires such a disproportionately high amount of firepower to take down.
Although the CRB-20 packs a pair of LLas, it cannot compete against mechs equipped with PPCs, LRMs, and smaller bore autocannons. The LLas combined only deliver an ACD of 6.67 at maximum range, which can sting, but these weapons are ineffective beyond 20". Without any true long-range weapons, the Crab is a poor fire support choice.
The Crab is an awesome point mech to lead the charge. It can provide covering fire on the way in, close quickly, and tie up enemy fire support mechs at point-blank. If enemy mechs target the CRB-20, it will be an inequitable exchange for them as the Crab can take an inordinate amount of damage for its size.
The CRB-20 is fairly optimized in its current configuration. Without wholesale change, there are not any basic modifications that can enhance the mech's overall performance. We looked at the impact of stripping the small laser and a half ton of armor (on the legs) to add another heatsink, but we only saw an increase of 4 points of average calculated damage over 12 turns and a loss of 5% in survivability; not a great trade in our opinion. In that regard, the CRB-20 is a solid choice in stock form and well worth the 1143 BV price tag.