Here's my take on the M65 question and on shorting in general.
The m65 differs I believe because of the varying decay of the bear etf vs the bull etf. The M65 is a longer, much longer indicator time wise and the decay difference will thro it off easier than a shorter time indicator like M12.
For the longest time I have always used SPY SPX or QQQ to generate signals to trade. Back in the past I would use options a lot of time to trade with, I switched to the leveraged ETFs when they became available. All my backtesting is done on the index charts. On daily charts I use SPY QQQ or IWM to get long or short signals. Thats on the big three. I have found using inverse charts SQQQ/TZA/SPXS put off different signals.
On 60m or less charts I use the SPXL/TQQQ etc
The sector charts are different in that harder to find the "base" chart. Those I still use the bull charts.
Not saying that trading off the inverse bear chart is wrong...Just that using the base charts has worked over the years for me and Duma.
Shorting for me has different rules, For me, using the exact same rules for shorting as going long has gotten me in trouble in the past. Again I use the base/bull chart for signals (big 3). Depending on the chart I wont short above the 50dma, rising m65, weekly chart in uptrend, and some others. Shorts are more violent in price action therefor I like to pounce quicker on a profit or exit.
Commodities are different, I basically have the same rules both long and short.
AI
