I have a Duragraph Red Nights. It's an OK pen. It's nice looking; the barrel and cap are perfectly well made. It doesn't post very well (I believe SBE Brown described it as "comically long" when posted) or securely. Inside, it is kind of a cheap pen. The feeds and collars are the same ones as in Jinhao 159, except the collars have proprietary threads. It's hit or miss whether the collar / feed will fit well into the section. I have 3 different collars and 5 - 10 feeds; it's hard to find a feed / collar combination for a given nib that fits well in the section.
The screw-in converter is a high point of the design.
As you might expect from the above comments about Jinhao 159s, the Duragraph will hold Goulet #6 nibs. This is, IMO, one of its best features. I've had 3 of the "half moon" branded Conklin nibs (2 Bock and 1 Jowo, I believe) and none of them have been very good. Right now I have a 1.1mm stub nib from Goulet in it. It is one of the old two-tone gold nibs. The pen looks sharp and writes well in this configuration.
I would not spend much money on a Duragraph. Some places sell them for $80+, and that is too much. I got mine from Goldspot when they were having a sale for somewhere in the $40 - $50 range (I can't remember exactly). That still seems a little high since you are probably going to have to replace the nib, but justifiable, especially if you really like the look (or really want that screw-in converter! ). Think of it as a super-deluxe Jinhao 159, because you will probably use it for the same kinds of things.