Has anyone tried the Kaco RETRO? It’s Parker 51 inspired, but in bright modern colours and with a fun looking clip. Specifically, is the nib any good?
Yes, I have 5 of the six colors and the nibs were all pretty nice. Fairly wet and pretty smooth. I would characterise them as Western fine.
BTW, this is “just” a Jinhao 51A with a different cap. So you could also go for the 51A. Those are also nice, but I don’t like the metal cap on those as it’s a bit sharp at the end.
Thanks, sounds interesting. Good to know about the sharp edged cap on the jinhao 51A because I would rather avoid that kind of thing.
Anyway, “Papier und Stift” have them for €8.95, which is the average price I see on eBay.
IMO the cap is the big improvement of the Kaco version. That said, the small ball at the end of the clip isn’t always perfect. I have one where you can see the glue (they used too much) and others where it is a bit cracked. But like you said, it’s less than 10€ and for that price it’s a great pen. Especially as it comes with two cartridges and a pretty nice converter (Schmidt I would guess).
Do you think the clip is sturdy, or would it break off easily if it is often clipped inside a notebook?
I think the clip should be sturdy enough for that.
Oh, and I could send you one. Either the blue or the black one. I really don’t need four of them. 
Oh, well that sounds like a generous offer 
. Blue would be good. I’ll message you.