Allow me to put some real numbers on braking things to try to answer your questions. I have taken the liberty to convert your basic question into metric measurements bacause over time I have developed dozens of metric based programmes including such things as lap time forecasting based on max G, HP and weight inputs. I am too lazy to convert any of these to non-metric units.
So I have inputted your question into braking from 225 kph to 145 kph and your braking 30 feet early to 9.1 meters early. I have also assumed that your vehicle has a maximum braking capability of 1G.
These numbers result in the 225 to 145 slowing effort will occur over 116.52 meters and take 2.27 seconds, (I am reporting in two decimal place accuracy). To compare this to your alternative of braking 9.1 meters earier I am assuming that the car will be held at 225 kph for these 9.1 meters which then adds .15 seconds to the late braking alternative. So this now has you taking 2.42 seconds to traverse 125.62 meters.
Now the early braking alternative finds you now braking at .93G and taking 2.44 seconds to traverse the same 125.62 m distance.
We can analyse any series of corners in a lap to find out what the effect on lap time is for early braking but this example shows that there is very little in it. I reality there are two factors which make the real scenario a bit worse for the early braker and those are that the late braker will continue to accelerate for those 9.1 extra meters and the early braker opens themselves up to an easier passing move by the late breaker if it is close enough. I have always found that optimum lap time comes from trail braking after the turn in has started and thereby getting some free and easy yaw control and resultant higher exit speed. The complexities of this are best kept to a differnet thread.
On the issue of how good are ABS systems I can throw in a few items from my experiences.
For both optimum braking and for optimum acceleration the best results occur with a bit of slip between rubber and road. In other words, for braking tyres are spinning at less than true vehicle speed and for acceleration they are spinning at greater than vehicle speed. The amount of slip for best performance is quite variable over a small range. The best slip is dependant on rubber compund, track suface and both track and tyre temperature. Others might offer better data but I find that the best performance is developed at slip ratios of 104 t0 112 percent of true vehicle speed. A good starting point for testing is 108%.
Now Greg has highlighted adjustable systems. I have nerver come across one that doesn't require a computer to set and I can absolutely advise that unless you have a good data collection system on your car that you will never get there by seat of the pants. I also know that your day to day driver sold by tthe tens of thousands have ABS systems that are set so far into the average driver's frailities that it is quite easy for a good driver to get into such a car, turn off the ABS and out perform the factory set ABS. Not the least of problems are that the slip ratios are set below optimum and the cycle rate is slow enough and wide enough that the tyes are constantly cycling outside the best real setting. A good driver and I note that there are not too many of these found day to day can feel the point of optimum slip and hold the car at that point without much if any cycling. I know from experience that even the the Vette ZO6 factory system can be beaten by a big margin by an accomplished driver. I also accept that in the electronic days of F1 that they developed systems that couldn't be beaten. The real problem was that these systems cost far more than the cost of 99.9% of the total cost of cars bought today.
So, if you really are good enough and can prove, it switch off the factory electronics for best performance on your evey day driver. Otherwise leave it on because even the factory settings will beat your performance. The proof only can come from lap time on the track.
Regards