If you played earlier SFCs, you'll recognize the K-Photon right away.
It's basically a new version of the old K-Dizzies. It fires twice as often as a F-Photon, and does 2/3 the damage. It also costs less prestige and uses less power.
So, *technically*, it is superior to the F-Photon in damage per turn, doing 12 damage in the time a F-Photon can do 9, and doing it for less energy. If you powered both with the same amount of energy (i.e. overload K-Photons to 8 energy), the K-Photon jumps up to 14 damage vs. 9 damage.
Heck, *technically*, a Quantum is [10 energy for 13 damage] while a K-Phot is [10 energy for 16 damage].
BUT:
1) Who cares how much PP weaps cost?
2) It doesn't seem to have the accuracy of the old DisRs <--the real killer
3) Due to the other SFC3 changes sabredancing doesn't work as well anymore
4) It costs more energy (relatively speaking) that the old DisRs
5) Many Kling hulls don't have designs that allow proper use of this weap.
6) It's hard to get a good shot every 2 turns.
7) Not having proxies is a killer.
Overall, I like the K-Phot better than the Poleron, and really like them on the smallest ships. K-Phots earn their keep when you can get behind a large ship and stay there for a couple of turns.