Steve,
You correctly point out the other problem with adding half to PC on buying. It not only may increase the size of the buys but it actually speeds buying because it increases the residual, and on the way down you want to go slow and keep a pause to prevent depleting cash too soon.
I've very optimistic about LD-AIM because once the trades start coming in, the returns may be multiplied by up to the leverage factor=virtual/(real holding). I expect in real life some problems with this method will reduce the returns, but still we are looking for much improved gains, more than just a few percent.
Adam
Market Data 
Markets 
AI
