I searched the FPN, but it seems that no one owns a new Conklin Mark Twain Crescent? Any experience with this pen?

I lust after one.
Does that count?

It writes smoothly. The fine nib puts down a wet line and is pretty close to what I find ideal for a medium. The nib doesn't really flex. If I add more pressure it just gushes more ink and makes the color of the line deeper. I don't see much in terms of variation in width. The example that I have is a reliable writer.

In terms of ink capacity in the sac, I've never really measured it. I tend to be fickle with my ink and cycle through different colors often.

Capped, its length is comparable to a Waterman Liaison, Parker 51, or a Pilot Vanishing Point. Its girth is closest to the Liaison and the Vanishing Point.

It feels pretty solid and has some more heft than the 51. Its weight is pretty darn close to a Vanishing Point and feels lighter than the Liaison.

Despite the "USA" on the nib, the pen is actually made in Italy by Visconti or Stipula.

I am wanting one of these pens too. I have a few crescent filler pens like my Stipula Saturno and my Visconti Copernicus. I love the way they fill and how the locking ring prevents the crescent from being pressed and having an accidental discharge!!

TNS

I had one once. Very briefly. I never did ink it, but I dipped it and wrote a few lines. The medium nib seemed to work well, and like others have said, it was a wet and smooth writer.

What nixed the deal for me, though, was the pen's weight and balance. I prefer to post pens, so keep that in mind. The pen was so top heavy with the cap posted it was very uncomfortable for me. Further, the wheel surrounding the crescent just happened to be in the worst possible place (the web between my thumb and forefinger).

Your mileage may vary, of course, but I couldn't get rid of the thing fast enough.