I am running an R4.1 machine for a while now, without any severe issues. If you run it, I would recommend:
- Before Updating critical components in Dom0:
- Check if the changes may effect your particular setup,
- check the changes in Qubes components, the Kernel and Xen on Github,
- check Github issues and the forum for complaints of other users.
- Be enogh familiar with different Linux distributions in general and Qubes in particular to fix or mitigate ‘little things’ occasionally.
- Do daily backups of VMs that are not completely unimportant to you. Have a ready-to-boot Qubes installer USB-Stick laying around, in case something goes completely sideways.
I initially moved to R4.1 because a piece of hardware that I wanted to use, was not supported yet. Since R4.0 was bumped to a newer kernel branch, I would be able to use it on that particular machine. But I guess I did move to R4.0, because I enjoy being a little more “on the edge”. (And am lazy to move.)
Regarding the speed issue I just wanted to cross reference this thread about VM boot times to anyone who does not know it yet.