Curved and Straight Tonearms

Sorry to disappoint you guys but properties like stiffness depend greatly on type of material, mechanical properties of the material, length to diameter ratio, you can't just say J shape better than straight pipe or vice versa.  
Same goes for resonance.  There seems to be a lot of misconceptions about resonance which works to the advantage of people that market "tweaks" and cones.  There is no way to tell which shape will be better. The resonant frequency of an arm tube will change when coupled with the headshell, cartridge, stylus, arm bearings and mount. The system (arm assembly) resonance is the all important parameter here.

If the azimuth cannot be fixed by the limited headshell adjustment, you really need to return the cart you bought, you have a cartridge problem not a tonearm problem.