optimus 123SVEA 123 stoves = 4,700 BTU'd Optimus 8r, and 99 = 3,300 BTU's. My own experience with both stoves seems to easily show the power difference between them. AsAn overview of the SVEA Optimus 123R Stove and Optimus Terra Weekender Cooking Pot Set. How to use, advantages and drawbacks.