It's not the ROM. It's the bluetooth stack(drivers) that are installed by HTC. They chose a Widcomm(I think) stack over the normal Microsoft one. It allowed them to do the fancy Bluetooth software that we use to setup/configure bluetooth, but it also causes incompatibility with a bunch of bluetooth devices (my Pioneer AVIC F90BT is definitely one of them!) as well as making some software that relies on being able to add stuff to the bluetooth driver (There's an app that will allow you to control your pc as if your phone was a mouse(screen) and keyboard(physical keyboard) which doesn't work because we're using the non-MS stack).
This issue definitely exists on stock Sprint ROM and MightyROM 11/26(I think /26, whatever
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