I did too. But installing them is a bit difficult with the tire mounted on the rim. So I'm adding the FOBO's as I replace tires. And, of course, I could remove a tire, break the bead, and swap out the valve, but, having just had a new Angel GT to play with, I discovered how stiff the carcass is. No way I can use wire ties to mount that tire - and I've heard the PR4's are the same. All this is to say that breaking the bead and trying to install a new 'T' valve stem would be quite difficult with the tires I have on my bike.I got some T-valves with my FOBO but they're steel and pretty heavy. I think I may just go with the ones I got from SlowBoy.
Before having a local repair shop mount and balance my new tires, I had considered weighting the sensor and my new valve stem on a kitchen scale (in grams) or a senstive reloading scale (did I really say that?). I had then planned to cut tire weights until one weighed the same and was going to glue it opposite the sensor and new valve stem (minus tthe weight of the old stem). Alas, since the shop balanced the wheel after installing the new stem, Fobo, and tire, this was not necessary.