The answer is not as simple as it may seem. Dyma-Serts will give you the best ROI over a longer period of time. But the disadvantage is that with its initial high cost, it takes awhile for you to see your Return. While the Magna Trap may not last as long but with its relatively low initial cost, you will see a return a lot quicker. So for an example the Dyma-Sert initial cost is around $600 for the dual disc grinder. At a rental rate of $120 per day, you will start to see your profit after 5 rentals. However the Dyma-Dots initial cost is around $200 for the Dual Disc Grinder and the rental rates for the Dots is also at $120 per day (despite the difference in the cost, it is EDCO’s recommendation that all accessories on the Dual Disc & Single Disc Grinder remain the same at $20 per accessory per day). So with the Dyma-Dots you will see a profit after the 2nd rental.
So I guess the answer is which option do you prefer, a better ROI that comes over a longer period of time (Dyma-Serts) or to get a quick ROI but may not be as much over a shorter period of time (Dyma-Dots).