But, I have learned a fix (secret fix) used at the Lexus Dealer for the thumb issue; is to drill a very small hole in this plate, this is to relieve pressure and allow the shaft to move as intended.
Adding a pressure relief hole to the slip yoke plug is a good idea. Spicer/Dana Slip yokes come with these holes from the factory. When you grease you cover the hole to force the grease to flow to the splines.
For those concerned about pressure on the driveline I think this is a better idea than under greasing.
#1 Grease is a good idea for improving flow in the shaft and maybe if you are using one of the stickier polymer greases like the Amsoil Offroad Grease.