I want to join this discussion to help those who, like me, were unsure whether buying an RSP1b was worth it or not.
Currently, I have an RTL-SDR and live in a metropolis with many signals and, consequently, a lot of noise and interference.
I'm trying to monitor a non-trunked P25 system in VHF and, despite receiving good signals, there are many errors in P25 decoding. In fact, SDRTrunk often fails to "hear" several frequencies with active transmissions.
Today, I purchased an SDRPlay RSP1b, but delivery takes 20 to 40 days to arrive here in Brazil.

As soon as I receive it, I'll be able to compare them and will return to enrich this post with more reports and experiences.