I have replaced my RB750Gr2 with the new version and it looked if all was working brilliantly however I now run more and more in troubles.
Since a two weeks my Phone could not login any more through IPsec and L2pPT so updated my RouterOS to current and then to RC and still I could not connect to IPsec/L2PT on the Mikrotik. I read that I could make it working again by using the VPN generator at the QuickSet page. When having used that I have first to correct all my IN/OUT addresses of my PPPoe out connection manually and the lines Filter/Nat/Mangle and on many many other places turn RED because. I have a new PPPoe out line in PPP that is hooked up bur not running because there is already a running PPPoe connection. And then IPsec/L2PT is still not working. 
I can’t tell QuickSet to use the current PPPoe connection and it generates every time a new connection. Very very frustrating.
Then looking again at the PPPoe I have the fibre coming in on port1 which is on VLAN and I can’t tell the switch to strip the VLAN when coming in and add when it is going back to my ISP. Maybe this function will be availble in a later RouterOS for the RB750Gr3. I have still to add a VLAN intermediate so my traffic goes from PPPoe–>VLAN7–>ISP and the otherway.
I have only one VLAN on that port so I don’t need filter different VLAN traffic.
I have now my Layer 7 filter running after many hours and it came down on switching off the the route cache (Fast Tracking). I had the impression that a new package always went through Mangle prerouting and when the NAT/filtering was determined there all the next packages could be off-loaded to Fast Tracking/Fast Path.
My Layer 7 filter is a simple one and I don’t need traffic on TCP port 80 that contains “Host: 123.123.123.123” in the first package.
I am thinking about putting for a time my RB750Gr2 back to give me a time-out just have a fresh start with the RB750Gr3 when it matured more in RouterOS.