TWSBI 540 just died, should I get a 580? I got a TWSBI 540 a couple of years ago that worked really well for a few months. After a while some cracks started developing in the barrel - no problem, TWSBI customer service was great and sent me a new one. 

A couple of months later, the band around the cap cracked right off - again, great customer service.

Recently it developed a leak around where the nib assembly screws into the barrel. I applied some silicone grease, and thought I'd fixed the problem.  Lent the pen to my wife who said the grip section felt loose, so I tightened it a little more and POP - nib assembly screw broke off in the body of the pen...

While the 540 was never particularly of any sentimental value, it was one of my favorite workhorse pens. Is it worth getting a 580? I'm mainly concerned about the quality of the material, and the design of the section (being secured to the body by the nib rather than by its own dedicated screw like in an Edison)