Trim
My airplane is mid range in weight, 975 lbs, and an o-360. It has a change in trim from high to low speed. I might be the only one. I have always been a curious about why my plane is this way.
It also wants different trim from heavy to light. If I am heavy (gas, bags, and passenger), it seems like neutral trim most of the way throught the speed range. If I am light (me and less than half tanks) it is in trim only at cruise speed (165 Knots, 55% power). If I am wide open throttle, level flight, I have a heavy right wing. If I pull the throttle to idle, I have a heavy left wing. Neither is that annoying if you don't fly for a long time at those speeds. However, if you want to make a fast trip, burn lots of gas, at least in my plane, you will want trim. Whether it is electric or manual is personal preference, but I like having the ability to trim. I went without trim for several years, then installed the spring manual trim. it works, but if I had it to do over again I would probably opt for electric trim. If you fly IFR, you definitely need it for final approach where most likely you will be slightly out of trim compared to cruise speed.
I'm interested in what others have to think about the change in trim with speed. Mine is pretty drastic. It goes from full right trim at high speed to full left trim at approach speeds, and I could probably use more trim than is available.