My experience, having both, is similar to what @shellfritsch described.
With the right control modules, you could probably build the functional equivalent of the squid with the 301. It would take some work, and more HP, but in the end it would be more customized, the sound wouldnāt degrade as much with pitch changes, youād have more sample time, and more cv control. But, it would take a lot of time not patching or performing to get there. Once it was set up, though, you could save it as a custom unit and bring it back whenever you wanted it.
That said, I have both and am glad I do. It lets me focus on using the 301 for more hi-fi or esoteric tasks, and encourages me to go deeper with it, rather than using it as a replacement for a module that might already exist, while the squid is ready to take on more immediate sampling and drum duties without requiring so much planning.