I think that I've bought all that pens I'm interested in. That last pen was a Pilot Custom 912 with a Waverly nib. It writes awesome, and looks like a a broad point using my normal grip. When held at a steeper angle, the line is thinner - the idea being that you can vary the angle and have a variable width line like you'd have with a brush pen. The effect is cool, but requires a ton of practice to pull off. It's too bad that Pilot doesn't offer this nib on cheaper pens because it'd be neat for more people to try out, and the Custom 912 are very expensive. The only other Pilot pen that offers the WA nib is a Custom 742, and that pen is just as pricey.
I've never done it myself, but I've heard of people doing it by just using more force. If that's not your style, you can always contact TWSBI to see if they would cover the repair under warranty. They used to be good about this, but I've heard that their customer service has deteriorated.
On the note, I think that the Eco is just outright better than the 580 (and the Vac 700R for that matter). It's the newer pen and TWSBI has never addressed the production issues with their older pens. This mostly hast to do with the body of the pen, and the nibs are made by Jowo, so your friend may be just unlucky.
My favorite is easily 4B - it has a beautiful color that's business-like enough to use in almost all situations, and it has the most beautiful sheen. It's just too bad that it's so hard to find, and so expensive when you can get it. For saner inks, I like Yama-Budo, Sherwood Green, and Aurora Black.
My go-to would be Bungubox. Even if you're not interested in their exclusive pens, they have an exclusive line of inks made by Sailor. This line has a ton of really cool inks that include the aforementioned 4B. You can see some of the other ones sampled here:
https://imgur.com/a/4RSO6. Note that these inks usually cost $45 USD online.
Do check their website before you go because they're not open every day:
http://bung-box.com/user_data/store.php
