I've been running Remastersys reliably since the 3.0.0 version came out. However I tend to be a bit conservative in my build approach. So there are a few "rules" that I currently stick to because they work for me.
I don't use Ubuntu because they keep changing the goal posts, and Remastersys/fragadelic has a hard time keeping up. I stick to Debian, and Debian, boring though it may seem, stays still long enough that you can use it long term.
I also keep within the repos except for a couple of minor apps like Pytyle. I guess that was a lesson learned from the days at PCLOS - if you go outside the repo it's not supported. I'm not paranoid about it, but I have done my fair share of compiling programs from source on my computer and it only takes one little update to some insignificant lib somewhere and you're back into hair-pulling mode. I don't have a problem with private repos or PPAs.
I don't remaster in a virtual machine - full stop. It's always bare metal, and if that isn't around then I can use a usb stick with a full install. In fact that is how VillageBox is currently done - it's on a stick that gets stuck into the test rig which has six partitions on the hard drive!!
The thing to remember with Remastersys is that if you are doing a "dist" build then rule Number No:1 is paramount - everything you want to see on boot/install MUST be in /etc/skel. No ifs or buts. That will also mean that the live ISO will be in root mode when you boot, so there are no user names or root passwords.
I have to say that I find Remastersys easier to use than Mylivecd on PCLOS because I only have to make sure /etc/skel is good. In Mylivecd the live ISO came out of the user set up, and the install came out of /etc/skel - so you had two lots of config stuff to keep track of.
My quest since leaving PCLOS has been to find a distro that I can reliably remaster, and I have to say that the combination of Debian and Remastersys is certainly serving me well. However, as the saying goes, YMMV!