Hi Oliver,
wouldn't straight hooks make things even worse, or am I wrong?
I have a complete SONOC set. All the edges are like that, and the drums sound better (to my ears) than the LPs, for an instance. Funky looks produce funky sounds
Do what you want, but I would keep it like that. Everything you do to the wood is irreversible.
The technique on the enú side is perhaps comparable to the bongo hembra, if at all. I don't know too much about darabukka technique, but what I have seen does not resemble okónkolo technique. In Matanzas they use finger strokes on the chachá in addition to slaps, while generally in Havana style only slaps are played on the chachá.
More body contact at the edge of the drum head inhibits the vibration of the membrane but adds more of the woody timbre of the body to the resonance, while producing more of a punchy attack from the skin.
Should you have any special questions you want to ask me personally, feel free to give me a call. My phone number is still the same for 30 years.
Thomas