Today I installed the newest test version 1.4.23 and proceeded to review how FSX-SE, P3D v4.4 and XP 11.30 behaved together.
My hub was tested on a closed LAN with each client having its own port. I used a C172 as my test aircraft as it is common to all my sims.
Generally the FSX and P3D systems did not exhibit any obvious differences from what was experienced in prior versions.
XPlane however is a different beast entirely. As indicated in various posts it is true that connecting the JoinFS using XP requires a series of careful steps; furthermore, any changes to XP whilst using the client results in a client simulator disconnection. This was not unexpected. Simply re-connecting then sim seemed to resolve the missing activity.
While connected and watching the JoinFS map that I use I noticed that the XP plane was apparently switching its orientation from 0 to 180 on a regular basis. Checking the sims there was no such change so it must be that the whazzup file might be changing and rendering the map in this fashion. I did have the new AI setting for whazzup activated on the hub.
When connecting I had XP set to have up to 10 AI available. While I had but two JoinFS participating aircraft the sim decided to generate more AI and they joined in on the fun.
Interestingly whilst testing I disconnected JoinFS on the XP system and restarted the flight. Although not connected the previous aircraft from P3D and FSX-SE appeared where they were before. Only if I shut down XP and restarted did that seem to go away. Upon reconnecting JoinFS those aircraft, as hoped, then came back where they were before.
I also made a short circuit of the test airport with P3D and XP in hopes of the XP sim plane catching up to the P3D plane so I could see how they showed up, if at all.
After taking off with P3D and establishing a GPS route to follow I used the same plan in XP. With the P3D plane going much slower I was able to catch up. Unlike P3D/FSX there appears to be no in-sim aircraft highlighting that could show an aircraft within the 10 mile range. Maybe there is but I do not know about it.
In any event I was able to spot the P3D plane from XP and follow it. Having no expectations I was pleased to see that there were no great impacts on either plane controls when both aircraft were close; however, I did notice that when I took a screen shot in XP the plane seemed upset and jostled about for a while.
Upon landing both aircraft I decide to see how the animations went. From P3D the lights and propeller animation from the XP plane seemed to work as expected. From XP there was no such concurrency.