Only problem I have ever seen posted about the flow thru sensors is that air flow can be slow when you are adding air. And they are somewhat larger than the non flow thru.
I have had the non flow thru for 5 years and am very happy with them. I typically add 3-4 pounds of air at the beginning of each travel season and never have to add air again until the next year. Have never had a tire lose air. As noted above, removing the sensor to add air is little more than removing a valve cap.
I did get a repeater as occasionally my monitor would temporarily lose contact with a sensor on my 35' 5er.
