There are way to many variables to nail that specific of an answer down for you.
It would depend on your surface more than anything, and personally I wouldn't really rely on the center diff for "steering response"
The center diff just supplies the the power to the front and rear diffs, which will effect your steering a lot more than the center ever would.
Typically for rough or loose tracks you're going to want a thinner diff fluid such as 5K.
If you're running on high traction tracks you're going to like a thicker fluid like the 7K for a more even 4x4 power distribution, IE more power to the rear.
While you could argue the thicker oil will give you more steering in the sense that it will allow you to whip the rear around on power, it can also just as easily make you're truck undriveable due to loosing stability coming on power to early on exit and breaking traction to quickly. At least that is my experience.
The way I understand the motor angled adjustment on the 3.0 is that it will supply more of a linear power band to the front and back rather than an exponential increase that an oil weight change alone would do. More of a constant if you will.
I am not sure that I am explaining it in a manner that makes sense, but that is what I took away from the understanding of what is happening by Losi stating "more 4wd feel"