Most of my experience has been with different planars (as well as with several bipolars), but I don't see much advantage to going with a smaller model instead of a larger one based on distance from the wall. The relevant factor is the path length for that first reflection off the wall behind the speakers, and that doesn't change with panel size. In general, the ear interprets early-arrival reflections as coloration and late-arrival ones as ambience.
In my opinion three feet out is definitely less than ideal, but it can still work well. I would consider diffusing the backwave, perhaps with ye olde fake ficus trees, and absorbing the backwave as a last resort. What you want to avoid is a strong, distinct, fairly early reflection. Using a large toe-in angle can also help.
Duke
dealer/manufacturer
In my opinion three feet out is definitely less than ideal, but it can still work well. I would consider diffusing the backwave, perhaps with ye olde fake ficus trees, and absorbing the backwave as a last resort. What you want to avoid is a strong, distinct, fairly early reflection. Using a large toe-in angle can also help.
Duke
dealer/manufacturer