I worked around BT and WiFi problems like this:
On your phone, after installing and booting the latest nightly (I'm on 20151006 as of this writing. Hope soon this will not be needed anymore):
Launch File Manager. You will need either Prompt or Root access mode on * => General settings;
change directory to /system/etc/firmware/wlan/prima, open WCNSS_qcom_cfg.ini
scroll down to gChannelBondingMode24GHz=1 (on line 306, towards the end) and change it to gChannelBondingMode24GHz=0
save and exit the editor
Switch on Bluetooth;
Settings => About phone => Status:
write down or copy to the clipboard your Bluetooth address (better yet, write it down when still stock);
Back to File Manager (with root access enabled).
in /data/etc/ create a file named bluetooth_bdaddr , in Properties>Permissions change owner/group to bluetooth and permissions to -RW--R---R--
open the newly created bluetooth_bdaddr with Editor, type or paste the Bluetooth address you wrote down or copied before
save and exit the editor;
if your are plagued by the "identical WiFi MAC address for all Xperia Z1C" (that is, you have collisions from more than one device with the same MAC on the same network segment)
In File Manager (with root access enabled).
in /data/etc/ create a file named wlan_macaddr0 , in Properties>Permissions change owner/group to wifi and permissions to -RW--R---R--
open the newly created wlan_macaddr0 with Editor, type or paste a new MAC address (e.g. 20:54:76:BA
A:55 - see below)
save and exit the editor;
You will want to use your original hardware MAC if you took note of it while still stock, or make some yourself using a prefix from Sony Mobile Communications (look for some on
http://standards-oui.ieee.org/oui.txt) and six random {0-9, A-F} characters
Of course you can perform all this using adb shell or local terminal and su, vi, chown, chmod.
Reboot your phone (will also update your WiFi MAC if you specified one) or enter/exit airplane mode;
WiFi should work as it used to until 20150927 (that is, no drops every few seconds). Bluetooth address will not change and screw pairings up all the time
In Settings => About phone => Status you should see the WiFi MAC and Bluetooth addresses you specified. They should both survive CM updates. You will need to put gChannelBondingMode24GHz back to 0 in WCNSS_qcom_cfg.ini until either channel bonding is fixed in the driver or the change is reverted upstream.
