The fact that after years of offering their models only with their Paragon decoders installed, they recently started offering "Stealth" models without Paragon decoders should answer your question. I suspect that so many modelers requested Paragonless models that they decided to make and sell them.
But in my experience the reliability issues aren't the biggest drawback. It is their performance (like long "reboot" times even with the slightest loss of track connectivity), and limited programmability of their function outputs. Paragon4 seems to be a bit better, but If I have a choice, I'll get a Stealth model and install a decoder of my choice.