Been on Sprint since I got the 6P and had to go through a SIM card hassle with Sprint.
(Sprint tech idiots giving out wrong SIM cards early on when the Nexus 6P and 5 were released).
With Sprint you will LOSE: Wi-Fi calling and their proprietary apps for Voicemail, Dialing, Contacts ...
The 6P can pickup a strong Sprint signal in any room in the house, #$@!* Samsung phones required a window for a signal.
Sprint charges for voicemail transcription, its free with Google.
Google's Voicemail SUCKS in set-up and features - it's bare bones.