OK, current KSBP baro 1012.7, current First Sensor baro ~4.4 miles away and an indeterminate # of feet elevation difference, 1028.0.
Looks like I need a -15.5 correction. I'm higher, so I think it should be a positive correction.
Ordinarily, the discrepancy would bother me, but since this is an analog voltage out, I'm OK with it. It would be interesting to see what the I2C reading is, but I don't have anything set up for that.
I did by 2 of them (one for a spare). I'll have to see what the other one reads.
I also want to program up a data logger module and trend graph and see how that looks.