anyone wanna hear why I though the A/M intermix might not be 1 in the early days?
Let's see if I can explain it as quickly as possible since I'm running out of time in the internet cafe!
Ok, so for those engineers out there, you know that when you have engine of some sort, both jet, rocket, and electric, basically the method of propulsion (for a newtonian kind of engine) is that you want to pour as much energy into the working fluid as possible (say, air and jet fuel for jet airplanes) and then expel it so that you can take advantage of all the energy stored in that fluid, right? Thinking of the intern combustion engine in cars is also a good way to think about it because everyone knows, even if they don't nkow what it does, that a turbocharger and supercharger both make cars go faster. Well, those accelerate the working fluid in the engine so that you get more potential energy when the spark plug sparks and ignites the fuel, so that you get a bigger "boom" and the piston is hit harder and pushes the crank shaft harder, thus, more power.
With the warp engines, the warp plasma isn't exactly a working fluid in the same Newtonian sense, however, if I correctly understand the technical schematics for how warp engines work, the warp plasma is basically an exteremely energized plasma that carries the energy from the A/M reaction to the warp nacelles and the warp coils which produces the warp field. Really, the only fictional physics here is 1. the dilithium crystal "controlling" the matter/antimatter reaction, and 2. the "warp coils" creating "warp particles" and in turn creating warp FIELDS. The electrified plasma part and the A/M reaction part are real physics, if extremely difficult engineering feats. So, you've got this energetic plasma that is intended to carry the energy to the warp coils. Well one of the biggest problems with modern day scramjet engines (engines they are trying to develop for single-stage-to-orbit spacecraft like the X-33 and VentureStar which were both cancelled -- spaceships that take off like an airplane and go into orbit and then land like the shuttle, instead of taking off vertically), one of the biggest problems is figuring out ways to develop "working fluids" that are capable of carrying more and more energy that they can use to propel the spacecraft into higher orbit, partially because the air become so thin at sub-orbital altitudes that you can't get much force out of it when you expel it through an engine manifold.
SO, since we know that warp coils require a tremendous amount of energy (only an A/M reaction or a microsingularity can provide enough) we know can suppose that it would make sense that an early design limitation is creating a working plasma, the warp plasma, capable of carrying enough energy to the warp nacelles. It's even concievable that while physicists had long known how to produce a matter/antimatter reaction (since even WE know HOW) given enough material of both substances, that they simply did not know how to design an electrified plasma capable of carrying all that energy. So if I were working on this problem, where the plasma could not absorb all of the energy being put out by the matter/antimatter reaction, the first thing that would come to MY mind for how to solve that, if the problem of creating a warp plasma capable of absorbing all that energy isn't going anywhere, would be to find a way to dull or dampen the amount of energy coming out of the reaction. One way to do that would be to push a greater-than-one-to-one ratio of the two reactants into the reaction chamber so that some portion of the remaining matter or antimatter actually uses up that extra energy that the plasma isn't capable of absorbing, by being destroyed. So basically if you had a 1.2:1 matter/antimatter ratio, then you'd have .2 amount of the matter or antimatter LEFT, after the reaction has completely annihilated both parts, and if that matter were swirling around in the chamber, it would likely be destroyed by some of the pure energy coming out of the reaction and just result in a bunch of subatomic particles and radiation.
In fact, this could also be used to explain, or to just claim if they've never said this, that early warp reactors were more dangerous and less safe than later ones. While this would be something you could just claim without reason because it make sense, if we take for fact what I've just described, then you would have, like I said, a bunch of extra subatomic particles and radiation being emitted as the extra matter or antimatter left over is being destroyed by the energy that is being bled off.
The one thing Starfleet engineers would no doubt NOT like about this idea is that it's pretty inefficient, because you are admittedly wasting a chunk of energy simply because you can't find a way to harness it all, but if it were a significant enough and difficult enough problem to solve, like they tried for 20 or 30 years and could never completely solve it, it is concievable that they would resort to such a solution if no others presented themselves.
It is also concievable that they HAVE improved the amount of energy they're able to absorb starting from the first warp ships to the Enterprise era, and continue to improve upon the efficiency in that regard up until the TNG era, where they presumably use a 1:1 ratio, given the question posed to Wesley Crusher during his Academy examination where he says "It's a trick question, the optimal ratio is just 1:1."
Since, maybe in the early days, they used like a 1.3:1 and then by Enterprise maybe they're using a 1.15:1 and by TOS era it's like 1.05:1 and then in TNG it's 1:1, something like that.