Ninja Squid is particularly useless given every single team is packing at least 1 Echolocator now. I'd rather not be marked for 12 seconds rendering my "stealth" useless when you can simply swim smarter to avoid being seen anyway.
I think it's easier to get kills once your marked because the other team becomes too confident and over extend themselves. It's hard to approach a charger who preemptively lays ink around themselves because they're anticipating an attack. It's even better with a weapon with a bubble because they won't know you have it if you stay in your ink.
I would also say you're not completely useless if you get marked. You could use that time to ink the floor, or be a distraction while your team with cold blooded goes offensive.
Swimming smarter is something that should be practiced but in an actual situation it may be too hard to do. When you see the dynamo rollers wind up their attacks or get pressured by bombs, swimming at a certain speed is another thing you will have to worry about. You could make the case of just trying to swim away, and sometimes it works, but other times you won't get away especially against a dynamo. Imo it's easier to trick your opponent into thinking where you might be. Most dynamo rollers will assume you will try to run away but I've found more success swimming towards them then run away after they've flick their ink.
In the end, it comes down to your preference. I've found more success running with squid ninja than with cold blooded. It might change when there's custom teams in August, who knows.