The Kakuno is one of my favorite pens!
I believe the Metropolitan and the Kakuno use the same nib. So if you like the Kakuno nib and are just looking for a more substantial body, the Metro should be a great fit. Pilot is know for good quality control, but it does sound like maybe you got a dud.
I agree that looks to be a Metropolitan. Great pens!
As @[email protected] said, you won't be able to see the ink level. When your line starts get get darker, thinner, and the pen starts to skip, it's time to refill. Or if the pen has been sitting for a while, maybe a quick cleaning.