The Rocketfish is a mediocre amp, at best. Good choices would be the PCT/Channel Master amps, the Antennas Direct 4 or 8 port amps, or Electroline amps. All are very, very good.
The need for an amp is determined by the available signal power and the cabling scheme's requirements. If you're moderately close to your towers and the signals are strong, then you can run a large number of splits with long cable runs and still have adequate power for reliable reception. OTOH, if you're in a weak to modest signal area, you may be pretty close to the digital cliff edge and it won't take much cabling or splitter loss to push your reception off the digital cliff. If you don't want to go through the math exercise, then just split the signal until it fails then back up some.