That said, Aurora is offering flex nibs in their newest Optima models. If you really want an Aurora flex nib, I encourage you to purchase one from Dan Smith. He can tweak the feed and nib for better flex and ink flow.
You can purchase the Pilot Custom Heritage 912 from Vanness Pens for $225.00. Although most (if not all) of the Aurora 88s with flex nibs are sold out, Optimas will be available in March (retail $650), and I suggest you contact Dan Smith to pre-order one of these. Franklin-Christoph offers numerous pen styles that accept the #6 SIG flex nib. Prices vary between models.
**Author’s note: My comparison omits one other modern flex pen: the Wahl-Eversharp Decoband (reviewed here). In terms of flex, this pen surpasses all three of the pens I reviewed above. However, two factors made me decide not to include it in this comparison. First, it truly is an oversized pen, much larger (and heavier) than the three pens discussed above. Second, it is a great deal more expensive (retail $850) than the other pens, especially the Franklin Christoph and the Pilot 912. Please read my review if you think an oversized pen would suit you best.