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.

Either can sound very good if matched to the rest and set up properly I believe but personally I’ve always had better luck with straight tonearms. But in practice fact of the matter is I’ve never had results with S arms like with straight and most quality tables these days use straight probably for good reason.

In the golden age of vinyl back in the 70s selling at Tech Hifi, Lafayette and Radio Shack I always levitated to tables with straight arms. Tracking was not nearly as reliable with massive S arm tables and carts. Often hard just to stay in the groove. Tracking a record is hard and mass and inertia is not your friend when it comes to tonearms with most records in practice. I prefered Thorens Philips and Linn over most Japanese tables with S arm.  Even Dual at comparable price points.  Maybe Micro Seiki......

I've gotten many years of listening pleasure out of a Linn Axis and even still a Dual 1264 with Goldring cart from 1981 still running in my second system.   Both straight arm. 

"In the golden age of vinyl back in the 70s selling at Tech Hifi, Lafayette and Radio Shack I always levitated to tables with straight arms. Tracking was not nearly as reliable with massive S arm tables and carts."

Perhaps the elegant and extremely effective SME "S" arms were overlooked? I recall one of the Stereophile sages declaring the SME Series III as his "gold standard" at the time.
Straight or curved really doesn't matter. What is most meaningful is how well any particular design is executed. I'd take a well-engineered "S" arm over a mediocre straight arm any day.

Dear @ericsch : I'm not an expert oon your Rega model but I know that exist an after market source where you can buy the VTA mechanism dedicated for your Rega tonearm.

Regards and enjoy the Music Not Distortions,
R.

What brf and Lewm said is correct.