Welcome to the Forum. Can you advise the dimensions (WxLxH) and shape of the man cave?
What amount of your time will be listening to music, and how much for movies, or concerts with Dolby HD or DTS Master HD.
Your Klipsch speakers are very sensitive (97dB @ 2.83 volts/1 meter) and don't need a lot of power to drive them, so your Yamaha ~115 watt / channel HTR-5960 should be more than adequate. Are they loud enough for you with the 5960 driving them? Do you usually turn it up to it's max?
An on line calculator indicates with just the F-3s running in stereo at 115 watts, you'd get in excess of 111 dB at a typical listening distance of 10 Feet. (That's over 120 dB at a little over 3 feet!) A 150 watt amp would only add about 1 dB over what is available at 115 Watts. At these volume levels hearing damage will occur with long exposures.
Most here (and me included) think Bi-Amping offers little to no benefit, but if it floats your boat, it only adds more cost to the Receiver, and reduces the available options. I'd save the $$ and add a second sub.