Well, I did hear a recent instance of the light shorting out, but no fire. It gives me pause about the overall quality.IMO they are very good for the price, people claim that they will burn down, but that happened with the older models, the new one should be fine and without any problem, you can buy one on ebay for less than $65 for 2X54Watts fixture. i have used this in the past and it produced good light which will keep you in medium light due to lack of good reflector.
+14 t5ho is a LOT of light. You won't need it and it is more likely go cause problems maintaining balance.
However, it can be nice to have the flexibility of two independently controlled banks of lights. By alternating banks during the day you can vary the source of light, providing more spread around the tank which will help achieve more uniform growth.
You can use different types of bulbs in the two banks. O have all daylight in one bank that I use in the am to early pm, then I switch to two flora bulbs for a softer, more colorful look late pm through evening.
So you don't need 4, but you can put them use if you have them.