I've used JL probes since the day they were released. Even with the "growing pains" of the app and connection, (which is largely fixed), I still love them and use them most of the time. I do like to have a manifold sometimes, and I will admit, the probe connection to the manifold is (from my experience) 100%, so I use it a lot too. With all the data that FP gives in it's app and the long range, I have no reason to use Testo. I've used the older Testo 550 and liked it a lot, but it just doesn't do what the JL system will do. Now does the new Testo read psychrometers and calculate capacity, TEET, and superheat/subcooling. and display that info on the manifold? I'm sure you could use MQ and get that type of data with them, but the JL system will work with MQ too, so again, no need to go Testo. I like Testo stuff, but they always seem to be a step behind the competition, if the new 550s was competing against the SMAN 360, then that would be a pretty fair comparison.
Just one man's opinion.