I’ve been running MSFS since it was launched on Xbox. It’s not yet perfect but my oh my it’s in the best shape it’s ever been on Xbox Series X. At its best it’s glorious 
I think you’re correct about possible memory limitations however I regularly take off from EGLL (Heathrow UK) regularly (Premium Deluxe version) with 100% live traffic and 100% ground traffic and as long as my internet connection is good and the server traffic is ok I rarely have a problem.
The 310 is quite heavy on the SIM - I’ve noticed that it causes reduced FPS in comparison to all my other planes (including PDMG DC6).
Overall the SIM runs very well on Xbox. I’m flying more than ever before (I stopped flying during some of the previous bug ridden updates which caused CTD on every flight). Thankfully those days are over and I can’t wait for the Boeing 747 and 787 Avionics Updates.
