I currently run 6 Omegas, and have owned many more. They all vary in pedal travel before 'bite'. I have known rear cylinders seize, never front ones; pedql travel was not affected. I change the brake fluid every 2 years, no change, so cause is not air in the system. My theory is wear in the master cylinder. I kept a spare off a car I scrapped, but have not yet bothered to fit it.
I find Omega brakes are excellent, as good as on any other car I have owned. My current brake niggle is my daughter's 2.6, she complains, brakes lack initial bite. I have driven it, and I can detect it. I have changed the pads, no change. Both front pistons move freely. Pedal travel is quite short. It might be the servo, or something else. At the moment she is driving the 3.2, while I MOT her 2.6. I await her report when she swops cars back again.
Shucks, all these cars are 17 tears old, it's a miracle they still go at all. My main brake challenge is the handbrake. The ingenious 'scissors' lever arrangement eventually gets stuck solid, then the handbrake still works, but without a mighty pull will not hold the car on a steep hill. The cure is to strip it down and free it, quite a big job, but rewarding.