Well, let me do the usual disclaimer that I'm not an expert, for sure...
It would seem to me that a well fitted dowel with grooves for glue flow would be stronger than a screw in most cases.... The main advantage to a dowel or biscuit, IMO, is the increase in gluing area... because if the joint fails, screws aren't going to help much...
I've done test joints with biscuits and then taken them apart a week later... In every case I had to break the joint before the biscuit let go..
mac
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