Unbalanced prop will lead to shake loosing motor mount and all relevant parts of the plane, moreover it produces strange noise and quivering on the whole planes. This is not a desirable setting to all radio control airplanes. I have flown too many airplanes with unbalance prop and they all end up with loosing engine mount and early worn-out ball bearing and, in the worse case, it rips off the motor from its seat. So the bigger propeller you have the bigger concern of the prop balancing you must be aware off.
On the nitro engine unbalanced prop makes rough and trembling sound on the whole fuselage. This is more noticeable when the engine revolution is increasing to the max, the wing tip and the tail will be quivering at such point. The degree of such problem is varied on the amount of false balance on the prop itself.
The stock propeller is always unbalanced, so you need to check this thing carefully prior to its installation. If you want to enjoy flying your radio control airplanes for a longer service hour you need to learn how to balance your prop. There are many balance stand to choose from, or making your own if you are a tools maker. The prop balancer is not expensive so having one in your workshop is not bad idea since you will need it regularly.
There are slightly different techniques to balance the prop which I really enjoy both. I hope you study both of them and if there are any better idea around please kindly leave the comment or link in this post.