leopord leader
The differences between the two SHAR's handling and the AV8B/GR5 onwards series is down to the wings.
Both SHARs had the 201 sq ft metal wing and all the AV8B/GR5s and onwards had the 230 sq ft graphite epoxy wing. As you might expect at high IMN the thin metal wig was superior giving less drag and negligible trim changes at high mach. The thicker wing had much more drag and very large trim changes in all three axes above .9 in a dive. So much so that on being asked by MACAIR (those were the days) to investigate the high mach handling in dives over Edwards in 1982 using FSD ship 2 (which aircraft had the latest intake/engine combination to reduce the proclivity to surge and so was being used to clear the aero envelope of the rest of the FSD fleet at Pax River) I likened the behaviour to that of a Vampire. As a result of this poor handling the aircraft entered service with a high mach limit unlike the FRS1 whch could be taken to 1.3 in a vertical dive at full chat. (If you got the starting height and pull through profile right - if not you only got about 1.2)
However the much more important handling difference between the two wings was at mid transition speeds. The metal wing had a very high rolling moment due to sideslip so at mid transition speed if you did not keep the vane in the middle you would roll uncontrollably and could even die in the process. I was well aware of this issue so on the first look at this characteristic on the new wing on the YAV8B (Aug 79) I eased the vane out very cautiously at 120kt and 8ADD. Imagine my surprise when I reached full rudder with no discernible roll and had to let go of the stick to see if I was carrying any aileron. Later on the proper B model when drooped ailerons were used to improve the STO heavyweight performance some rolling moment with sideslip did emerge but it was not serious needing less than 1/4 aileron at full rudder.
I don't know what you include in your 'handling' term but the metal wing was very inferior so far as turn performance at low or medium speeds went. This is not surprising given the combination of extra area, thicker section and addition of LERX. At high speeds of course both wings were g limited.
Hope that gives you a feel. Don't ask me about a radar comparison between the FA2 and the B+ 'cos I never flew either radar. However my mates would suggest that the B+ was better than the FRS1 but not as good as the FA2.
JF