Mike, the O-1 will work even better with the 11 Second oil than the 5160 will. Doug, you are correct that grain growth is a serious problem when it actually occurs, edge stability and impact toughness drop to worthless levels, it is really nasty, so it is not a boogeyman in that it actually exists, but it is not really a threat once one has control over temperature.
For some time guys who work in forges have been leaving the impression that grain growth is an ever present danger ready to leap out and get you whenever you drop your guard for a second, but this is mostly because they use a forge, or a 6,000F torch flame to heat treat. In reality grain growth is not dependent on the phase of the moon or not measuring every heat to the fraction of a second, it is temperature dependent. Once you have even moderate control over temperature grain growth should no longer be a problem.
Grain growth phobia seems to be the last vestiges of the edge packing myth, i.e. only the hammer of skilled smiths, or some guys "speicial" techniques, have the magical powers to control grain size, so I must apologize that I am rather proactive in dispelling it. Recrystallization works in a very set and predictable way. First, as your heat nears Ac1, you will begin to nucleate tiny embryonic seed grains in the existing grain boundaries. Then when Ac1 is achieved the allotropic shift occurs that allows those new guys to form into actual grains by absorbing the old grains. Equilibrium is the magic word since it is all driven by very basic physics, it is a process of going from high energy to a lower energy equilibrium. The nucleation will be at points of higher energy in the matrix and will feed off that energy until equilibrium is achieved, at this point you now have a whole new set of grains. This new set of grains will have undissolved carbide at their periphery keeping things stable and defining the grain boundaries, as well as other particles from the steel making process, this is why you have not one, but several critical (arrest) temperatures, one lower (Ac1) and three higher (Ac2 for the Currie point, Ac3 for hypoeutectoids, and AcCm for hypereutectoids). Ac1 is the recrystallization temperature, but for a hypereutectoid AcCm is the point where all those extra particles are dissolved and the grain is free to grow as temperature overcomes equilibrium. But with a hypereutectoid you are going to do even worse things for edge stability than enlarged grain before you reach AcCm.
But once equilibrium is achieved, it is exactly that, equilibrium, and it will take greater temperatures to overcome it. When you set an oven that can hold a precise temperature, you can maintain equilibrium and grain size, but in a forge you can lose concentration and quickly spike the temp 100F without even knowing it, and so those who use unregulated heat sources often get a bit more gun shy of grain growth. The other thing that adds to the confusion is that I know of very few smiths that actually have the means of measuring grain size properly. Instead almost all who say they are observing grain size are doing it via fracture methods. The problem here is that it is subjective to interpretation. Fully hard steel fractures in a different mode than steel with mixed microstructures/phases. With a little pearlite mixed in, or even with a little tempering, the fractured grain surface will have a rougher and coarser look. Over my years I have watched many veteran bladesmiths show the “smoother” look on the edge of an edge quenched knife as proof of edge packing, despite the fact that it was the heat treatment, not the hammer, or even grain size that accounted for that appearance.
So you are correct that grain growth is bad and a real threat to knife quality, but like burning the steel while forging, it is easily avoided with a little care. If you slip some O-1 into a 1475F oven, that oven is going to have to malfunction in some way to enlarge the grain, but if you heat the same blade with a torch all it is going take is a split second of letting your mind wander and grain growth is a very clear and present danger.