I have no issues with texting over wifi, the only way texting will not work over wifi is if you are getting group messages or include any multimedia items such as videos, pics or audios. Group messaging is considered MMS so it will only send/receive once service is restored. Any input is welcome.
Loving this feature since my building is really old and service does not penetrate inside the building, its not just Sprint but the same applies to the carriers. Recently installed my old Magic Box 2 at my office and at least one side of the building has LTE and great speeds. No more 3G or no service inside the building.