I dirty-flashed lilac and poplar-dsds, and both seem to have installed with no issues. My lilac phone, however, still has that longstanding audio problem during calls (i.e. lack of audio in the earspeaker), so someday I will probably reflash stock, then upgrade to iodé again to see if that fixes it. It’s currently not a problem, though, because…
I’ve switched to the non-VoLTE poplar-dsds, ported my mobile nbr to JMP.chat, and added a data-only SIM with fairly cheap international coverage. I can dial numbers either through the normal phone dialer (using the JMP/XMPP account) or directly from the Cheogram app; the latter handles SMS, MMS, and group messages over XMPP with no issues.
One potential problem is that JMP can’t call the emergency nbr (911 in the U.S.), but the phone itself can (like all smartphones) if there’s a tower within range. Emergency services can’t call you back, though, if there’s no regular SIM inserted. I’ll probably find a cheap paygo SIM as backup, and keep it in one of the SIM slots. [EDIT: Useless in the poplar due to lack of VoLTE, I know, but I’ll probably eventually buy one of the newer dual-SIM Xperias.]
Thanks, as always, for the builds! 
EDIT: Call audio now working again on the XZ1 Compact, possibly because of new SIM card, different carrier.