Normally I don't tend to say much, I just sit back and take it all in; but this time I think I'll enter the fray.
First I see no reason why shifting gear to gear would harm any automatic transmission. It's designed to be able to do that; however if you don't have a manual valve body (a modified valve body, which allows the operator to determine shift points) I don't really see what the benefit would be. At this point I don't own an SVX (about to change) but I assume that the computer still controlls the shift points like in every other electronically controlled transmission.
Now as someone who has built and dynoed several automatic transmissions I would agree that power braking might not be the thing you want to do in a stock SVX.
These are just my opinions of course, so take it with a grain of salt.
Off subject (sort of) but has anyone thought of having an SVX automatic modified with a manual valve body? As I am about to buy a couple of SVXs I think that might be a project I am willing to take on. Never ripped apart a Subaru automatic before but it functions the same as any other automatic does, which means in theory it can be done. What would the benefit be? Manual shifting; of course!
Now out of curiosity where can I get a manual that details the rebuild of a 4EAT? Basically I need to have flow charts for the clutch packs etc.