I was checking to see if anyone has used seller & bellot lrg rifle primers. If so, are they worth using?

I've tried them but they are a little too small in diameter, they are .20866 (5,3 mm)and a slightly loose fit, not much resistance when seating them.
So far I've only used them in low-pressure loads ok (2000 fps in a .308), don't know how they would perform at regular pressures.

a lot of s&b brass has a correspondingly smaller primer pocket.
which has caused some grief.

So true. Both their rifle and pistol brass have tighter than regular primer pockets and thus their primers are smaller.
They in fact have a dimension standard of their own.
Besides some quality issues, that's why many stay away from S&B altogether (SonofaBitch).

I have just received my S&B primers. I have not shot them yet, but hopefully In the next couple of weeks. Here is what I have noticed so far.

A. The priming matrix is royal blue.
B. The cups are brass colored.
C. They seat shallower than domestic primers.
D. They are a good fit in new Winchester & Remington brass of different lots.
E. They still fit well in twice and three times fired brass.
F. In 30 year old LC brass with numerous hunting loadings, they were not so tight but acceptable.