FACT: With PSU and shipping included, 3 Tubes costs less than a single SP20 and will provide 2.4 Th/s compared to 1.7 Th/s.
But you also have to pay and support
2.4kW if you buy the
tubes where if you buy the
SP20 you only need to pay and support for
1.1kW.
Here is another FACT: You will not see any dividends in September.