Not a scientific option, but take it for what it's worth. Last time I got new skates, I dropped down a half a size, which dropped me down to a smaller runner. On of the things I noticed was I was a little less stable. At first, I thought was just new skate adjustment. I thought if I just did some edge work etc my feel for the skates would improve and that instability would go away. After about 6 months of working, things didn't improve much. In fact, it exasperated some of the flaws in my skating, one of which was getting on to my toes too much. I find it incredibly easy to get onto my toes, too easy. I think part of it is because I'm a 175 guy with size 4.5 feet.
That's when I started to look into profiling and in my research, I came upon some things that might explain what was happening. From what I read, the middle part of the runner is pretty much the same on all size runners if they all have the same profile, but for obvious reason, with smaller runners, the transition curving up towards the toe is a more aggressive/steeper transition. So, with the smaller runner, when I shift weight and rock forward or backward, there's a steeper drop, so to speak, which makes things a bit more wobbly.
To address this I went to a larger profile. I settled on a 13' profile for a while, and now, I'm on a 13/26' profile with a negative pitch. For many, that's incredibly flat, but I find these work great.for me.
So going back to what some of the pros and cons are, from my experience, the smaller runner will make it easier to shift your weight onto your toes,with the opposite happening with the larger runner. Going to a larger runner, may allow you to go to a smaller profile and retain the same relative stability.
Any ways, that's my experience.