New firmware with two important fixes, 2nd and 5th in the list below, issues that we have seen on .25 and particularly .26
I've upgraded 13 MXs throughout the day, starting when I originally posted, so far without issues.
NoNAT was initially one of the main reasons for us using it, though we haven't actually used NoNAT yet... We do use the load balancing a lot in the VPN and just connectivity, but that might be in 14.x?
It does also have IKEv2 for 3rd party VPNs
18x MXs now on 15.27 a mix of 64,65,67,84 and 100 models. 84 and 100 models are in HA pairs for SD-WAN, others single for edge protection. Haven't upgraded 250s yet.