Here's a good link
http://dominikburch.ch/Bata/Bata%20general.htmlI wonder the same thing about weather they may differ in havanah and matanzas myself? They do sound very similar, except for the fact that a lot of guy's from havanah
have a lot more flores and stuff...
I know you won't be able to find transcriptions in the Amira book as it only deals with the oro seco. I believe Chacha derives from the seco toque for Chango...
That section of the Chango toque is definitly where that chacha ( not 4 , not 6 feel ) comes from... You know , Fixx

Hope this helps