While I do think TWSBI makes a clearly superior pen in the $50-$75 range, I just got a 698 and it blows the eco out of the freaking water.
Sure, you don't have the out-of-box nib selection, but even still, for less than a TWSBI eco, you can have a 698 F, pick up a pilot penmanship in EF (nibs and feeds 100% interchangable) and a pilot plumix with a ~1mm stub, and have three completely different pens that all have swappable nibs.
Or, if you have a metro in M or F, get an EF or F 698 and switch the nibs around to your liking.
The 698 is basically a pen that pilot should be making and selling at $30. If this was a pilot piston pen that used their steel nibs and could be had with their standard range of EF, F, M, and B/BB stub, I'd have like 3 or 4. As it is, I have to buy 3 or 4 698's now, because these pens are AMAZING platforms since they not only write well, but are insanely comfortable in the hand (the grip section is REALLY good, think a longer platinum 3776 section, and gently tapered, unlike the weirdly ramped metro section that kind of ruins the pen for me)
I have two minor gripes that absolutely don't put me off the pen. When the blind cap is pushed down, it wiggles about 1/2 mm left and right . now that I'm used to it, I just find myself playing with it more than annoyed by it.
And I do wish that they'd figured out how to make it post. But it's long enough, I don't find it problematic.
I went with the color I've never seen anyone else with, demonstrator with a white cap and blind cap. I thought it might look weird, but I actually really dig it, the white contrasts the ink in the barrel really nicely (thusfar diamine brandy dazzle looks awesome in it)