Tim,
I fly coupled approaches in my 6 a lot. I have a Dynon system. I have found that in the RV6, 90 is a bit slow. To me, when I am trying to maintain 90 knots, the plane is like a boat just about on plane. You are heading down hill and it wants to speed up. You slow the engine and it slows, then too much. So you add power again. You speed goes up and down. I fly the approach at 110 to 120 knots, no flaps. Then as I get down to below 1000 ft or so AGL, I pull power, and then add flaps when I have the runway in sight. With these planes landing a little hot or long is not a problem. I’m still turning off most runways at the mid point. The plane is just so much more stable at 120 knots, it’s one less thing to worry about. Like others have said I had to turn up my gain and sensitivity a lot also.
Another thing about RVs and auto pilots. Since the plane has such a broad speed range, setting the autopilot to work right at cruise means it might be sluggish at approach speeds. Setting it for approach speeds means it may be a little twitchy at cruise. I have mine set for approach speeds, 120 knots. And it is a little quick at cruise, but I like it that way. On low approaches, I tend to start slowing down after the FAF. Yes, it is harder to control at 90 knots than 130, but I don't need to deal with slowing down at low altitudes in the soup.
RF