>>>> AIM does not appear to have an advantage during upward periods<<<<
First if you are not 100% invested in stocks at the bottom you can't possibly perform as well as buy and hold.
Second AIM has you selling as the market goes up so you are not holding as much stock at the top.
That is like saying AIM does better as a stock declines compared to buy and hold. Well of course it does.
First you are starting with 50% in cash so you have invested to lose and second you are buying more at lower prices.
You need to compare AIM to a diversified portfolio thru at LEAST one market cycle.