Force =Mass x Acceleration (the force comes from the thrust of the same motor being used and is constant for the example)
Velocity=acceleration x time + initial velocity
Therefore final velocity, all things being equal, IS related to mass. Does that actually matter? The answer is, it depends.....
For the 4 " Patriot example all 3 angle of attack graphs show the CP moving back in the transonic region and becoming more stable. For my example at a 4 deg angle of attack the rocket becomes significantly less stable and the CP moves forward. Stability is not just dependant on nose weight added. If your rocket has marginal stability and is going to go into the transonic region it's important to know where that stability is at all times.
What is the answer for your rocket, I don't know. But at least run the RAS Aero sim and find out if you're going to be launching a J510 in a 4 " Patriot.
(no-one here would use the largest motor that fits and launch it...
) And don't let the sim program you are using let you think that CP is a constant.
Finally, just because a design has flown successfully on a lower power motor, does not mean it will work on a higher power motor. It probably will..... But.....All of the above.
Good luck and clear skies...
Now , how ARE you going to glue that weight in?