Nice that the installer works with:
dom0_max_vcpus=1 dom0_vcpus_pin=1
None of the changes made at boot time, are stored permanently. Since my machine doesn’t complete the “initial setup” correctly (current suspect is the Lenovo BIOS/ACPI issues) on the second boot, I’ve not attempted to make it permanent. I think you should be able to make it permanent, by editing
/etc/default/grub from a running/completed installation:
It’s been suggested, that you might get a better experience, is you can use:
clocksource=tsc tsc=unstable hpetbroadcast=0
as the permanent arguments to Xen (post install && initial setup). Since my machine doesn’t get that far, I’ve not had a chance to test it. 
Wrt. release, the Qubes OS 4.1.2 should be just around the corner – so it might make sense to just use/test 4.1.2-rcX (and report issues you find).