Hi.
This is the very subject I too have been pondering about.
I've bought the PG Blues and Abraxas sets for two guitars but the Nailbombs also sound superb and probably more flexible than many think.
In consultation with Tim over my order for the above, I came away thinking Alnico provides detail and the A4 and A5 magnets clean up very well despite being a hot pickup.
Ceramic is bold, fast tracking but more modern in vibe and frequency response.
Ceramic has it's positive merits but Alnico will sound a tad more vocal and have it's vintage heritage come through under gain but especially when backed off.
I'm thinking of going for a ceramic Nailbomb for the bridge and a ceramic A4 version for the neck for the reasons outlined above.
However, a ceramic Nailbomb for the bridge and an Abraxas A4 at the neck will capture the best of both worlds, m'thinks!
Tim is the guru, though.
His advice is always excellent.
Good luck and happy playing.
regards
Jeff Makor