I have the ET-73 going on 2 years now, works fine. The only issue is that it will loose signal when I am in bed on overnight cooks due to too many walls and distance from my smoker.
(2 story duplex - smoker in back, bedroom in front of house upstairs)
If the distance is not an issue the cheaper ET-73 will work fine.
Bark Bros. Competition BBQ • Humphrey's BB' Cube (in production) • 22.5 WSM • 22.5" OTS • BLUE Performer • Beer • Wood • Orange Thermapen