When in doubt I try to lean more towards what I don't have a lot of, like for me, depending on whose broad it is, it may be a tad too big for normal writing with me so I like to go kind of middle of the road, that what I did when I got another Goulet Nib, grabbed a medium because I already have a EF and a 1.5mm of the same brand of nibs.
And honestly if it were possible I would have stuck that faber-castell nib onto my Monteverde. But the faber-castell's body isn't too bad, the rubberized section is decent, and I don't feel like I'm going to snap the pen in half.
I bought this pen today @ Hyatts' in Clarence (Buffalo store is closed Sundays) for $45 and they were nice enough to put an order in for me on that converter you mentioned. Took your advice and went with the M nib. It feels great in the hand unposted - (the cap makes it a little too long) - finish is lovely and that nib is something from just a quick dip. A full ink job will have to wait till that convertor arrives. Thanks once again!