I can tell you basic functionality, DTMF, Call Hold, Transfer, Forward, Conference, and G711 Fax work, fax is a tad spotty sometimes but if you have pretty solid telco it's reliable for most applications... Call Park and resiliency with the 3300 works great but I don't those features work since the 5000 doesn't support them, but knowing how it works in the SIP box, if you used the same credentials in two systems it should fail over if the main controller failed.
I can't really speak to most of the other features, never used them... We typically use them with the 3300, have 50-60 units deployed, mostly the 24-port boxes, but we have a handful on the 5000 and they are just simple.