Re: gibbo '57 vs sd '59
The Gibson '57 Classics are an alnico 2 humbucker inspired by the earliest version of the Seth Lover designed Gibson paf that specified alnico 2 for the magnet. So is the Duncan Seth Lover...though the Seth has a more pleasing tone, IMO and actually sounds more like a genuine vintage '57 Gibson paf than the Gibson '57 Classic.
By 1959 Gibson was using alnico 2, 4 and 5 more or less indiscriminantly.
The Duncan 59 is an alnico 5 humbucker inspired by the Gibson '59 paf and those that were made in the early '60's...like the pickups Clapton used in his '64 SG when he played with Cream, or those Eric Johnson has in his early 60's Gibson ES-335 that he uses to emulate Clapton's Cream tone.
I think the 59 has plenty of mids, but not as much mids as if it were an alnico 2 humbucker like the Seth, Pearly Gates or Antiquity. All four are differant versions of the same '57 through '60 Gibson paf humbuckers...
You might like to read the humbucking pickup shootout these guys did:
http://www.legendarytones.com Click on guitars to find the reviews.
There's also a new article on Clapton's Gear choices in the 60's and most of it coincides with the work we did here on the forum a few months ago regarding Clapton's gear with Cream and John Mayall.