Of the five SME arms I own, only the most recent, a 309 purchased during the year before they stopped selling arms, has the coloured logo. It is also the only one with serial # information on the box, stickered on.
My arms go back to the 80s.
The 2 IVs, the IV.Vi, and the 309 all include the hyphen. The other arm, a series 3, does not apply.
Bill