If your joints are good, carpenters glue is stronger than the surrounding wood. But I have always used URAC. I prefer W splices too, for the extra surface area, which is absolutely essential and basically "free."
Steves comments about flat surfaces, properly angled for the setback or deflex you want I'd add. Also having a perfect 90 on your bandsaw.
I don't pin splices, but the rationale is to get the fit just like you want, deflex/reflex or whatever, then run the pin holes. Then when you assemble w/ glue it's easy to get back exactly to that config w/ the dowels as an aid. Anybody whose done many splices knows they can get pretty squirrelly once the slick glue gets on. Pins do not improve the joint necessarily, but should not much impair the joint either. Least not enough to matter, on a properly fit W. Some really good bowyers do pin, but for the aforementioned reason.
Right or wrong, I try to put my arrow pass at the top, if you will, of the W.