Going astray from the OP:
I'm not sure how elaborate the alchy systems out there are. I really have no idea how many systems are available to the turbo guys and have never used alchy on my cars.
I presume the most simple systems turn on the pump when needed using a switching device. If that's correct, then extra voltage from the booster will cause the pump to run at a higher speed, adding more alcohol to the mix. This would make the alchy system very difficult to precisely administer, since system voltages are all over the place.
However, if the pump speed varies with demand based on a controller, then I would think the system voltage has less of an effect on alcohol delivery. Still not highly precise, but much better than just blasting the pump with a switch.
Finally, if the pump speed is constant and there is a solenoid for the alcohol delivery, controlled by PWM (similar to our factory wastegate control), the system voltage would probably have very little effect on precise metering of the alcohol.
And, regarding the OP (Voltage 101):
Did you ever notice the car losing power, or the exhaust "popping" and backfiring at the top of the RPM, top of 3rd. gear? That is usually what happens when you run out of spark. And, you run out of spark every time when you run low on voltage.
What everyone should consider with a volt booster is the positive effect voltage has on our ignition system. The ignition system voltage level is critical to a healthy spark. It's the voltage that gets your spark in the efficient range. Average current consumption, in fact, DROPS as the RPM increases, so voltage control is necessary to achieve an acceptable spark under load. That's the main reason you would want to use a volt booster, as it does more for your ignition system than for your fuel system.
Assuming your fuel pump puts out more volume and pressure at 12 volts than you actually need under worst-case scenario, and is not "on the fence" with delivery, the fuel system should be more than adequate, so a system voltage drop of a volt or so won't have any real effect on your WOT blasts.
But your alternator will fill the battery as needed. Everyone who monitors WOT blasts will almost always record a voltage drop in the scan, as the RPM's hit the top of each gear, especially at the top of third gear (when you're near the end of the quarter mile run - and when you need a hot spark the most). With all that power being consumed, the alternator can't keep up with the 13+ volts required by the ignition system. So the voltage drops. It doesn't matter so much what size of alternator you use, nor does the current output really matter - those 240 amp beasts won't give you more voltage. What really matters is that voltage. That is exactly why you use the volt booster - to compensate for that voltage sag. There aren't too many other ways to do it the way the volt booster does it. It's taking over where the alternator/battery system falls off. You can't really call it a "band-aid" since it's not really covering up for something, but rather compensating for a design fault. Most vehicles out there can handle a slight drop at WOT, but our cars need all the help they can get, because we've been pushing the design envelope forever.
Off the soapbox for now.