The 4:1 transformer balun works well for VHF & UHF; the PCB balun works better for UHF than for VHF. The new UHF antennas with a built-in PCB balun don't pick up VHF channels as well as the older UHF antennas that used a separate 4:1 transformer balun.
So, it really depends upon your application.
If you need a low-loss balun for one channel, then the best choice is a DIY halfwave 4:1 coaxial balun cut for the frequency of that channel.
Awhile back, ADTech said that NEWER 91XG used a Printed Circuit Board (PCB) balun which uses unequal stripline delays to form the equivalent of a Coax Balun, which ONLY works on UHF Band and severely attenuates Hi-VHF. You probably could figure out a way to replace the PCB Balun....perhaps ADTech can help...