Cimorene

So the compatible converter is Lamy Z28 (5 Usd at jetpens) and the compatible nibs are Z50 (14 usd at jetpens). The Safari is about 30 bucks, I think. So actually the twsbi eco would be slightly cheaper.

A bit less durable, but otoh, there's something soothing about a piston-filled pen instead of a pen with a separate piston adapter. It holds more ink and it just feels conceptually more elegant because it's direct! When you have the piston converter inside the barrel, there's all this wasted space because of the screw end. And I suppose it also eliminates the chance of the converter coming loose and leaking ink that way, but that probably isn't a very big risk. Piston pens can still leak - around the feed usually, I think.

But the Twsbi is potentially just nicer and more fun to hold, fill with ink, and write with as well, although not everyone's taste is the same of course.

I've just read some reviews and it seems twsbi doesn't have as good quality control for nibs as Lamy and it's possible that you would get one that is scratchy or writes with great difficulty. Lamy nibs are all tested before shipping, so they are the safest in that respect. But Lamy stubs are reported to be a little less smoothed and more "italic".

I have a Kaweco Sport stub nib I like, and the smoothness of the Kaweco stub is apparently a known thing...but I can't recommend using Sports with anything but standard international cartridges, the other filling systems just aren't reliable enough. To me it's too much bother refilling these cartridges with the syringe anymore although that is possible - I just bought cartridges for them. And Kaweco is also very well known for nib quality issues, much worse than Twsbi (I've never heard this about their nibs before and I've owned three with no serious problems). That said, Kaweco has other larger pens that work fine with converters, I've just never bought one.