Well, it's hard to prove a negative (although never say never) but I have not seen any problems myself, nor heard of anything from the field yet. If you see anything that you suspect is a 6.3 only problem, definitely send it in please.
UPDATE - I belatedly noticed that your app-tag was the LGPL version of Sideview Utils, rather than the more recent versions. I'm afraid I have not tested the old 1.3.5 version and I haven't had any feedback about it in a while. The latest version has always been freely available under our own internal use license.
I totally understand why many people would at first shy away from custom license agreements,
but the LGPL licensing only went as far as 1.3.5 which dates back to July of 2012, so 3+ years ago. To get a sense of how vast a gulf of bugfixes and improvements separates 1.3.5 from 3.3.6, just browse through the Sideview Utils release notes page a little.
http://sideviewapps.com/apps/sideview-utils/release-notes/
If I hear about any problems that 1.3.5 has just specific to 6.3, let me know. In my mind it has hundreds of problems though and that's why those problems were fixed!
And I'm not trying to sell you but fyi we also do have very modestly priced commercial licensing, and the more standard looking commercial software term license agreement with support may be easier to get through legal+procurement than the public free license agreement. Email me with any questions at all.
