I've done a bunch of them over the years but the one I just did for the GMC is the only one that has had vibration problems.
I think that this was due to using a shaft with a dent in it.
We usually take a hack saw and cut through the tube next to the weld. Just cut into it a bit at a time to just cut the tube and not the end piece.
We then put an old ring compressor around the driveshaft to use as a guide to cut the shaft.
Like mentioned above make sure that the ends are in phase and true.
The problem that I have found with using a chop saw is that most of them just do not cut true after being used for a while.
Sending off an order for a new shaft is great but not everyone has the ready cash to put out for one and not all project rigs are intended for high speed driving.