I'm not sure what he thinks is changed about jails. The default way that they're managed by the startup scripts changed in 10, but the underlying jail technology is no different. Actually, the old way still works in 10. There's talk about removing it in 11, but it's not decided for certain yet, and since the startup process is just shell scripts, you could always copy that one over from 10 or write your own if you just can't stand jail.conf.
So I think it must be a misunderstanding or communication issue. FreeBSD focuses on evolutionary development, and one of their guiding principles is POLA - Principle of Least Astonishment. In other words, what will be the least surprising to existing sysadmins. It's in place specifically to prevent that kind of radical change. The few radical changes that were necessary (GEOM, atacam, the new usb stack) bent over backwards to maintain compatibility with existing tools and procedures.
Couldn't tell you. He and I engage in frequent discussions about heavy weight vs light weight virtualization mostly. He's more the idealist. I'm the more pragmatic. He has his ideas of how things should work. I prefer they just work, not give me trouble, and update without issues.
I have tried FreeBSD 7, 8, 9, and 10. I even keep a KVM VM built with 10. But it's a base image. FreeBSD 7, 8, & 9 worked quite well except I'd run into issues with ports. Every time it would be with portmaster during an upgrade. My experiences with 10 have been better since I now avoid the ports and just use packages. It needs more speed with the disk subsystem. My Debian file server is about twice as fast doing the same task. Both use same underlying storage system. Virtualized of course. lvm thin on top of md raid configured as a raid 10 far using 4 disks on a KVM host. I've gone through the zfs tuning guide. Tried tuning it. Did get better performance out of the VM but never could at least match the Debian VM even at 4x ram and proper tuning for an 8GB machine. Also tried it with UFS but it still couldn't match the Debian fileserver.
Since it sounds like you're a user of FreeBSD and have had better luck with it than I have, I would be interested to know how well bhyve works. And how it compares to KVM or ESXi. Where is it strong. Where is it weak. For my purposes, the hypervisor would need to be running some kind of advanced filesystem like ZFS in a raid 10 config on local disks. zvols would be my preferred choice over qcow2 or raw images. It would have little more than the hypervisor itself, a ntp server, and perhaps dns/dhcp/pxe/tftp. DNSMASQ comes to mind. And it should be able to run other hypervisors as guests with nested guests.