I can only vouch for two of the nibs the original poster mentioned: the Lamy 1.1 & the smaller but similar 14K Sailor Music nib.
Out of the box, the untipped Lamy 1.1 nib showed a lot more line-width-variation than the Sailor factory Music nib. The Lamy 1.1 seemed surprisingly stub-like for an inexpensive stainless nib. The Sailor Ms nib tried hard to be like a big stub, but did not succeed as a versatile daily writer.
Before sending my Sailor 1911S pens (each fitted with a 14K Ms nib) for regrinding, I tried first to write with each Music nib, just as it came out of the box. I was hoping to find a winner among them, a factory nib I could keep.
Compared to an expertly ground stub or cursive italic, the Sailor Ms nib seemed without character. While this style of nib may be very good at writing musical notation, I don't think it is really intended for writing Western script.
However, the Sailor Ms makes an excellent starting point for nib customization. There's a big chunk of tipping material available on these traditional two-tine nibs. Every edged Sailor nib I own by Mr Mottishaw or Mr. Masuyama has started out as a 14K Ms nib. At present I have five such nibs in my stable, from 0.6 mm to 1.1 mm. I'm very pleased with them all.
The overall shape & width of the tipping is very similar on both Sailor nib series (14K & 21K); the body sizes of the nibs of course differ. More than likely, the writing characteristics of the 21K Ms nib would be similar to the 14K Ms. Perhaps the 21K nib would be a little less stiff.
My 0.02 CAD. Other folks experience may differ.
Edited by tinta, 18 March 2016 - 19:26.
*Sailor 1911S, Black/gold, 14c. 0.8 mm. stub(JM) *1911S blue "Colours", 14c. H-B "M" BLS (PB)
*2 Sailor 1911-M Burgundy/gold pens: 14c. 0.6 mm. "round-nosed" CI (MM) & 1.1 mm. CI (JM)
*Sailor Pro-Gear Slim Spec. Ed. "Fire",14c. (factory) "H-B"
*2 Kaweco SPECIAL fountain pens: 14c."M" "B",-0.5 mm & 0.7 mm stubs (PB)
*Kaweco Stainless Steel Lilliput, 14c "B" -0.6 mm. stub (PB)
*Montblanc 254, 14c. "BB" (1.1 mm?) flügelfeder factory stub