I model in HOn3
I do that and I'm very happy with the operation of my Sergent Sharon type couplers. I also use true to scale coupler buffer openings on my scratch built cars. This has required a track radius of greater than 20" radius to prevent the couplers from binding in the track plan I am designing. I personally feel that HOn3 trains look best on prototypical radii and not ridiculously tight, non-protypical curves like 12 to 19 inch radii. Not to mention that most brass locomotives won't negotiate track radii of less than 22 inch radius without shorting out or derailing. I had already settled on 24 inch radius so there were little to no foreseen problems to begin with. But I tested smaller radius until I found the point at which the couplers would bind in curved track and cause the cars to derail. (It was any curvature less than 20 inch radius) What happened more often than not, was that the trucks bound against the center beams before the coupled coupler faces did.
One of the things that I discovered in this process was that nearly 50% of of the end to end/side to side movement of (2) coupled cars takes place at the knuckle faces. Just like the prototypes do. Imagine that! On D&RG narrow gauge equipment there is only about 6 to 8 inches maximum of left and right coupler movement in the draft gear compartment. The rest of the needed left to right and right to left movement is done at the interlocked coupler faces.
I the first place, the "Friction Spring" is only there to keep the coupler in the proper position for re-coupling The other important thing I discovered in my testing was that my cars without the "Friction Spring" mounted in a close to scale draft gear box were always within the required coupler gathering range even on curves. I finally reasoned that this was because the couplers were always within the near to the center line alignment with the rest of the car.
So your answer is YES! You can leave the springs out if you so choose. But other precautions may be needed for their operating smoothness.
The S scale people have come up with a different solution for this spring. There is now a coupler box for S scale Sergents that mounts the "Friction Spring" at the back end of the couplers shank instead of in it's middle at the pivot point. This causes the couplers to always load to the center line of the cars after uncoupling.
I designed a coupler box for HOn3 that does this as well and tried to sell them at Shapeways. But I personally don't feel that this is really necessary. (I only sold one set). There was a decry that Sergents don't work like Kadee 714 couplers (I for one am great-full for that on SOOOOOO many levels!) because they don't self-center. Kadee 714 coupler boxes can be modified to do the same thing as my Shapeways product at no extra cost at all if you are replacing Kadee 714's with Sergents.
I hope this helped