AAN has the right of it.
As a brief background, I put through an order directly with TWSBI for a 580 with M nib, a 580 with 1.1 Stub nib, a VAC700 with M nib, a VAC20 bottle and a Diamond 50 bottle. Received the pens and inked straight away. None wrote well or in a usable fashion, so I de-inked the pens and cleaned with soapy water. Re-inked the pens and tried again and had the same results. De-inked the pens again and gave another good cleaned, this time totally disassembling the pen and scrubbing the feed with a soft toothbrush. Re-inked the pens and tried again.
The pen's still suffered from the same issues with poor flow, hard starts and skipping. Contacted TWSBI and was told to squeeze the nib wings and then push the nib down on a hard surface and spread the tines. I tried this (although the 580 with M nib had issues with ink simply gushing from the pen when it was writing, so this process was going to make that worse) and then attempted to write with the pens again. The VAC700 was writing a bit wetter, but all still suffered the same issues with skipping and hard starts as well as writing inconsistently. So i took the pens apart again, cleaned them all again, used a toothpick or a staple (can't remember what exactly I used) to make sure the channels in the feeds were clear and clean, adjusted the nibs again and tried writing again.
Still the pens have the same issues. They are simply not writing in a fashion which is suitable or acceptable for a pen (I tried using them in a meeting at work and could not for the life of me to get them to work. Luckily I had some reliable Kaweco's on me, so I was able to take notes with them). I contacted TWSBI again saying that the pens still don't write acceptably. To which I was told to send the pens back to the USA. I replied saying the cost of doing so was huge. I then got no further correspondence from TWSBI until Speedy has asked me to email again in this thread.
So, end of the line is 3 out of 3 pens on my order direct from TWSBI were non-functional OUT OF THE BOX. I have spent more time on trying to get these pens writing than any other pen I own, and certainly more than is acceptable for a brand new product. The products clearly can't have gone through QC, as they simply don't function. TWSBI's response has been to say I have to spend a further 60% of the price of a new 580 in order to send the pens back to them for 'repair' (hell, I could almost buy 2 replacement nib units for the TWSBI's for the same price...).
As for expecting TWSBI to stump the bill for shipping, that comes down to the situation. If the pens were fine out of the box and then started developing problems I of course would expect to have to pay shipping back to be repaired. If I had received 1 pen that was faulty I would also expect TWSBI to ask me to send it in to them. However when all pens on an order have the same issues and have had the issues since the boxes were opened (so a clear QC control issue. I would be saying at this stage there is no QC), so the products are clearly not of merchantable quality or fit for purpose, I would be expecting TWSBI to be doing more to resolve it. I would also expect some sort of a apology from TWSBI that all the pens were defective out of the box, but I have received nothing of the sort.
Also, considering there have been several reports around the place of TWSBI simply sending out new nib units and not asking customers to send the entire pen in and suffer the further shipping costs, I have to wonder why this has not been offered in my case. As Speedy has said, not point spending more on shipping than the worth of the pen, but that's EXACTLY what TWSBI is asking me to do.
As a bit of an anecdote, I bought a Kaweco Sport pen from a retailer here in Aus (they are also the distributor and cover the warranty for the Kaweco's in Aus) and when I got it it had issues with how it was writing. I tried adjusting it, but had no joy. So I contacted the retailer/distributor and asked for some advice. They apologized right off and said they will simply replace the pen. They said not to both sending it back to them (as this was going to be a further cost to me) and I could simply do what I wanted with the defective one. The next day I received a package from them. In it was a replacement Kaweco, a replacement nib unit for the defective pen, and a Kaweco cartridge holder with 4 carts of blue ink.
I also experienced an issue with a Lamy Safari I purchased. I unknowingly filled it with a contaminated batch of J Herbin ink. It was all sludgy and sticky, and it totally gummed up the feed and the pen would not work. So I contacted Lamy here in Aus and explained what happened. They then sent me out a new feed unit and nib, and a box of ink carts (their Red/Orange colour ones). They did this KNOWING that the issues with the pen were not a manufacturing or quality issue of theirs.
Currently collection:Lamy Safari's x5, Lamy Al Star's x3, Lamy Studio's x2, A Lamy 2000, Kaweco Sports/AL Sports x7, Noodlers pens (Konrad and Ahab) x10, Noodlers Konrad Ebonite x2, Hero 616 x10, Reform 1745 x10, Sailor 1911m x2, Sailor 1911 Realo x3, Sailor Pro Gear Realo x2, Sailor Pro Gear Imperial Black, Sailor 1911 Sterling Silver, Visconti Opera Club Cherry Juice (M Dreamtouch Nib), Visconti Opera Elements x3 (Amber and Black with M Dreamtouch Nib, Blue with M Gold Nib), Visconti Homo Sapiens Steel Age Maxi, Visconti Homo Sapiens Bronze Age, Montblanc 146 Le Grande... Plus I am sure I have forgotten some.