I measured my hand using both methods and technically I'm 4-3/4 according to the "finger top to crease line" method but I'm only 6' tall.
I did buy 4-1/2 PSGTs recently since that's all TW had left and the Shock Shield grip is thick enough to bump up a size.
When I demo using a 4-3/8 grip it feels way to small to me.
Only on Talk Tennis can you find people who believe
that 10 feet of lead tape has no effect on a frame...