A nose ring is necessary for high precision flight like Pattern. Snaps are violent enough to cause a slight gyration which, although quickly damped, can be "felt" by the experienced pilots who fly these birds. For sport, it won't be noticed much. Nevertheless, a nose ring will help if it can be installed.

As the engine is revved up, thrust moves it forward about 1/32" which is something you can see. You also see the cylinder rotate on the axis a bit in the opposite direction of prop rotation The engine is supported at it's cg and the cg is centered on the rubber isolation rings. Resultant side moments are zero.

My DLE55's sensor location for example was modified from stock to accommodate a nose ring. I intend to use the engine in my latest Pattern design. Running the combo in a 13 pound, 2 meter Extra was an eyeopener power and thrust wise. And the Pattern plane won't weigh much more than 11 pounds. Would be able to fly the bird at very low throttle setting, very slowly, with instant thrust on demand