I wanted to follow up on my experience after installing the Fotodiox Tough E-Mount LT on my A7r today. It took only minutes to install and appears to have improved the lens wiggle quite a bit, but it is not completely gone. Just to be sure, and before deciding to keep it, I put the orignal e-mount back, checked the wiggle and confirmed the Fotodiox was inded an improvement and was worth keeping. For reference, I grabbed the only other camera I have right now, a Fuji XE-1, and could also detect slight flex in its mount. So I'm happy with this setup now...time to go out and shoot more...
Thanks to MarcB83 (Marc), navmannz (John) and 40Driggs for weighing in on this topic.
Jon