I asked this question over at stackoverflow and am now taking it here: http://stackoverflow.com/questions/20672254/ie11-crystal-reports-printmode-activex-now-displaying-pdf-prompt-instead-of
It's a simple straight-forward question. IE11 is breaking the ActiveX plug-in used for printing from the Crystal Report Viewer. All the pretty pictures are in the link I provided. But the jist is that for my ActiveX Print Mode reports, the PDF dialog is presented now instead of the normal Printer dialog (unless I use Compatibility Mode)
Other details:
I am using the Crystal Reports that comes with Microsoft Visual Studio 2008. For the life of me I can't remember how this got installed on one of my browser's (maybe an install from Visual Studio?) ... but I've been deploying the Crystal Print Control 10.5 (32-bit; version: 10.5.1.2285).
And as mentioned in the stackoverflow post I have all ActiveX settings enabled and ActiveX Filtering off.