When the MAX upgrade is available for my aspen units, I think I'm going to go ahead and finish my panel.  I have an STEC 50 with altitude hold.  I have manual trim.  I currently have a 430W and will fly it until it gives me problems.  At that point, I'll probably swap it for a 440.  In my situation, does the 3100 do enough to justify such an investment?  Since the form factor is different, I'd have to pay to modify the panel if I were to decide to add it later.