I'm not sure if DC designs has a dedicated forum, or I should contact Just Flight for feedback... and post here too.. I believe Dean is active on AVSIM.. 

I mentioned over in the screenshot forum about needing to baby the autopilot and autothrottle systems, as in not asking either of them to make large changes. One needs to get in the ballpark with airspeed and altitude more so than with other airliners. Now that I have completed a flight from Belfast (??  Trying out my latest UK2000 purchase 😉 ) to NYC, I feel that both of the systems should be somewhat more responsive in their reactions. In my case, the altitude hold lets Concorde balloon up and down, porpoising past the desired altitude, eventually settling down, beware if you're only a few thousand AGL or indeed trying to autoland...

IAS hold or Mach hold is equally sluggish, although be careful the AT doesn't select reheat when trying to build up to an airspeed value...

When on approach to KJFK - I ended up doing 3 go-arounds to 22R. With a standard 30 degree intercept, Concorde overshot the localiser one way and then the other. Given that the ILS only comes into range at about 25 miles away.... I tried a lesser intercept angle and a similar thing happened. At least the approach speed of 210 knots was stable... When I selected ILS (glideslope intercept) she dived for the floor.

I ended up disconnecting the autopilot and approaching manually. I managed to land OK - ground effect is certainly modelled, as is having to fly the nosewheel down! 

I noted that when selecting a different altitude, the AP instantly defaults to a 3000 fpm ascent or descent depending..  This doesn't help the altitude overshoot IMO.. 

Have any other AVSIM members who have this product experienced the lack of AP and AT response? Can this be altered in the cfg file or a possible update if so warranted?

Perhaps my technique needs some finesse, but I'd like to see if I'm not the only one 

WORKAROUND for changing altitude:

Deselect ALT HOLD, dial in new altitude.

Dial in appropriate climb/descent rate.

Re- select ALT HOLD and off she goes quite respectably.

The default value which the V/S is set to in the aircraft config file is 3000 . This can easily be changed however.

Notwithstanding weather injection, the DCD Concorde Autopilot responds better on approach IF one doesn't have too much fuel remaining... . I didn't alter the payload, but in cataloguing a couple of flights Manchester to Manchester (take off, reverse course, then come back within 30 miles so as to pick up the ILS), she fared a bit better with only about 15000 pounds remaining . Still porpoised a bit on GS interception...

There should be an update coming soon according to Dean's input on the Just Flight forum.