People are posting impressive dyno charts every week that show that injection can stave off detonation, but as a potential user who is interested in safety more than power, the prospect of uneven distribution doesn't sit well with me. But without testing, and measuring with a 4-channel cylinder pressure setup or something like that, I can only speculate on how significant it is. Even a 4-channel EGT setup would be of limited value since RPM variations would move the the peaks and valleys between cylinders, faster than the EGT sensors could react.
7000 RPM is about 120hz. Given four alcohol injectors that can operate at that rate, I'd be satisfied. Anything less makes me wonder. It seems to me that the ideal setup would would use two-injectors per cylinder, with one set of injectors spraying fuel and the other spraying water/alcohol, but apparently nobody makes injectors that are safe for water or methanol. (I've been searching a lot over the last couple days, planning to use Megasquirt or other cheap ECU to drive the extra set of injectors.) With a second set of injectors, you could fire the extra injectors using signals that was based on the fuel injector signals for each cylinder, and be guaranteed proper distribution. And I like the idea of using a send-return system with boost-referenced pressure, just like fuel systems. And given how reliably fuel system components perform every day in millions of cars, I'd be a lot less worried about component failure. But alas, nobody seems to make compatible injectors.