Purple is literally just red build
Purple is actually a red but comes equipped with Combat readiness. Combat readiness 1 could prove to be an improvement in damage per appropriate conditions. Lv 1 engraving that can cause potential 12% additional damage is rather absurd of cheap Lost ark gold.
But... you must take into consideration the potential cost and the gold cost to be able to build this. Red builds already have many engravings: master brawler, lone Knight grudge, master brawler and supercharge at 3 levels. The breaking of any of these to earn your CR1 is an absolute no! That means for purple to be effective... you'll require at least 4x3 +. If you can pay for the items then you'll probably need to expand the size to 5x3 plus 1 using either barricade or cursed doll to be your 5th. This will require a lot of effort and money. It's a better option to go with the 4x3 plus 2 adren + 1 CR that, to be honest, isn't the best option.
At the time of the absolute peak of character builds we'll be able to access possibilities of building 5x3+2 characters. That would mean we'd have precisely the number of required number of nodes to reach. Without going into the maths of it, 5x3+1 + 1 isn't feasible, since the +1s could exceed the required 5 points for their respective levels. The best choice for reds at this point is adrenaline 2, in along with 5x3 listed in the previous paragraph. That means you'd be comparing the CR1 against adrenaline 2, and the latter is superior in terms of damage.
In the meantime, until we have our 5x3+2 build, CR1 will compete for the +1 slot, along with Arden 1. In fact, CR1 has the upper hand for damage in raw form, but should you choose to take Arden 1 you could drop any crits on a ring, or ear and play fast instead.
It's also important to consider the duration of the uptime for the CR1. In order to keep it at its maximum damage potential, it's necessary to continue to take hits. In a guardian raid it's not that bad. They aren't a lot of damage and usually don't have downtime.
Legion raids are a distinct story. This setting is where the micro-optimizations will be crucial. There are many instances where the boss is invulnerable, followed by an attack burst window. The CR stacks will decrease. Also, there are plenty of counters that can cause you to lose your damage abilities and the similarly and you won't get hit enough to keep your stacks. The bosses strike harder than guardians and usually also have other buffs that your combat stance is unable to be able to block with Lost ark gold. While your shield might be larger however, you're not equipped with the shield generation blue does... therefore prolonged times of taking hits to increase CR stacks the best option. You really want to Avoid being hit as much as is possible.
Tldr: If you turn purple, CR becomes your +2. The slot competes with adrenaline. If you're not good, take CR and if you're not, then go for adrenaline.