Are you familiar with past TWSBI cracking issues?
I do. From what I understand, all the cracking issues have something to do with the nibs being removable and the collar not being attached properly when the nib was screwed back to the barrel. Thus, it causes stress to the collar or the threads on the barrel and cracks it. On TWSBI Eco, only the piston unit is screwed onto the barrel. The nib is friction-fit. So, my guess would be, there's not much cracking that might happen. That's just my speculation.