Subject: Re: GTR1: rrs vs. rsi
So for using it to backtest with parameter values I can easily get, it seems like the best rule to use would be "ratio(aprc(1,1),aprc(1,252)) top 10"

If you use unadjusted pricing for your selections, aprc is the correct factor. If you use adjusted pricing (dividends, splits, etc.), you should use gprc for backtesting.

Aussi