May I suggest you, if you really plan to release cross-platform version one day, to release a test version « asap » just for feedback.
I'm mostly a Windows user but when I release my first game I remember doing the same thing you did (waiting a solid v1 and then release build for Linux & Mac OS ...even buy a Mac for this purpose...). That's when I received aggressive comments from users of other OS because I wasn't using certain audio or video drivers. I then found myself in a tricky situation where these users were commenting negatively on a game that worked very well, but only on Windows. Bringing unnecessary stress to the bug-fixing post RC phase.
Today, this may no more be the case with commercial engines, emulation & more robust cross-platform driver support, but I thought that this experience might be useful to you.