I emailed them over a week ago and have received no reply, other than the standard automated "we received your email" response. I may just stay on Mavericks and 1P4.
It took a while before I got a reply back, but they do always get back to you. On the email I got, they apologised for the length of time it took for them to reply, as they were swamped with emails.
I was surprised they gave me a code for to get the Mac Appstore version free of charge as I originally purchased 1Password when it was on version 3. Since then, for version 4 and now 5, I haven't needed to pay for the update. I must admit that there are no other developers I can think of that would give free upgrades for two later versions. A lesson some other developers could follow.