Real owners rate these about evenly: 77% of 275 Pilot Vanishing Point owners recommend it, vs 77% of 394 for the TWSBI Diamond 580.
Verdicts aggregated from Reddit, enthusiast forums, and YouTube owner comments — affiliate reviews excluded. Sample sizes differ; judge accordingly. How we score
“I cannot recommend it highly enough”— @kateriewing on YouTube
“My beloved Pilot Vanishing Point, inked with Sailor Sei-boku. Writes smoother and cleaner than anything else I’ve used, the retracting mechanism is impressively effective at preventing the nib from drying out”— VeryConsciousWater on Reddit
“I have Document Black and whilst it's incredibly well-behaved on pretty much any paper and is a pleasure to write with, it clogged my Pilot Vanishing Point pretty badly and has definitely stained a few pens.”— Strange_Cod249 on Reddit
“TWSBI is the only pen I own that you can set aside for months, pick up and use without issues. They are airtight beyond imagination.”— @Erin-Thor on YouTube
“I love them both.”— @ShariArts on YouTube
“I vastly prefer my ECO to the 580. I ended up selling the latter, it just didn't feel or write as well, but the ECO just feels right and doesn't lose anything if you ask me!”— @markdryden8240 on YouTube