The Stradic and Saros use the same drag material and drag design. Both reels have equally smooth drags so there is no real difference there. The main difference is in the oscillation.
The Saros uses an oscillation gear with Super Slow Oscillation. This allows the line to stack flatter and more consistent than a normal oscillation speed. The standard oscillation gear design will make line stack more like an hour glass. This is because of the dwell time at the top and bottom of the stroke. Its not as noticeable with mono as it is with braided line. There are several ways around this such as an elliptical shaped oscillation gear (which we use on some models) but its not relevant to this topic.
The Stradic uses a worm gear design. This stacks the line very precisely compared to an oscillation gear. The use of braided line on spinning reels is increasing. This design is absolutely the best for use with braided lines. We use the new Aerowrap II worm gear. This is a fancy name for a two speed oscillation. By making the speed change the line will never dig into itself under pressure. This is very important with braided line. The benefit is that casting performance improves due to reduced friction on the line. We also tuned the speed to work with our new spool design to further eliminate line twist. It works in the same manner with mono and FC lines.
After all of this I would say if you plan to use braided line then I would go with the Stradic for improved performance. The Saros will handle the job, but the Stradic will be better. If you will use mono or FC then either reel will be fine with the Stradic still offering slightly better casting performance.