I have looked into this some. I am not an expert, but have had emails and conversations with experts. This is what I have found:
With the new compound bows and releases of today, we might need to redefine, “too stiff”. For 20 yd spots.. I do not think there is too stiff. GT claims that you can shoot their 30x pro’s and their UL pro 22’s from 40 to 70 lbs… There are things you need to do to tune them in but they shoot fine.
I am here to tell you that I am a believer as I shoot both 30X and UL pro 22’s and they go where aimed.. (If I could only aim better at times…), They fly well. I shoot about 62lbs. My daughter also has both and she shoots them as well, but at about 38 to 40 lbs. They fly well for her as well.
So, I do not think there is too stiff in this case. There is too weak though and arrows will act funcky if too weak for the bow setup. There are several threads about this I think.
Now, for outdoor NFAA, or 3-d, where we get shots 30, 40, 60, etc.., yards as possible.. I am not convinced that arrows like UL pro 22 are appropriate. They may be, but I have no experience with them. There may be a “too stiff here, but I am not sure. I say this as I think stiffness plays a more critical role at long distances.. and I have not personally, yet, tried these on the longer shots. GT would say they are fine I bet. I have heard of them being tried but do not know the results. I think my bow they would be ok… not so sure about my daughter’s at 40 lbs.