Hi Al
Have you had this #9 long? I am wondering if the blade is new?
I have three LN block planes with A2 blades plus a bunch (!) of LV BU planes also with A2 blades. Of note, I have a LV LA Jack that gets used on a shooting board and has used the same A2 blade ground and honed at 25 degrees for some years now.
A2 is not recommended to be ground under 30 degrees. It is interesting that it is supplied at 25 degrees! In my experience most A2 blades seem to do just fine at 25 degrees. Some new A2 blades, however, chip a smidgeon when first used. I have had this with both LN and LV blades. What appears to be the cause (I am surmising) is that the tempering process has left the edge of the bevel a little over hard and, therefore, brittle. When I have ground them back (again a smidgeon) the blades have behaved themselves thereafter.
I tend to opt for A2 over O1 steel because it has better abrasion resistance. The woods I use, such as Jarrah, are very abrasive as they contain highish levels of silica. A2 just last longer than O1. Here in Oz many take the option of HSS and D2, which is another story when it comes to honing.
I think that the resistance to A2 comes from those who find sharpening more time consuming. This may be a result of inappropriate sharpening media. Using Shaptons, for example, makes it as easy as one could imagine. And I find no difference in the degree of "sharpness" against O1. I suspect (not having tried this) that oil stones would not work well.
I think that if I worked with less abrasive woods, I too would just go for O1. It really is easier to hone. But A2 offers better endurance.
Regards from Perth
Derek