If we react to every market swing, we are probably going to lose a lot of money.
Eg. If we thought last Friday that the market was going to fall more and sold out from REITs to buy bonds (which is what ARI might have done), then we would be feeling stuck now when it rebounded.
If the market keeps rising, then we may be forced to buy in at a higher price (or lose out on gains as the market rises). This would end up with the classic "Sell Low, Buy High" situation. (ARI may end up automatically doing this for you. The big question is how effective ARI is at predicting future market movements...)
It isn't just a question of rising or falling markets. That is more relevant if we are comparing 100% stocks versus a stock & bond portfolio. ARI has the added component of market timing, and so the big question is how good the system is at timing the market...