Not sure how far it extends the range, but my smoker just happens to be close to the house so I don't have any issues with the range and it works great. There is no charge for the app, it is free with the thermometer.
I swear by ThermoWorks. I've still got an old Weber probe unit that I just use for baked potatoes (getting an accurate internal temp was the key to getting the best baked potatoes), but I've currently got two TW ThermaPen thermometers (one for the garage/smokehouse, and one that has a built-in IR thermometer in my kitchen so I can know the temp on my stovetop griddle), a Signals unit (supports up to 4 probes, including an ambient), a Billows fan (which plugs into the Signals and helps to control the temperature in a charcoal smoker based on the ambient probe reading), and a Time Stack (just a fancy kitchen timer). All of their products that I've ever used are fantastic.
Thermoworks is the king. They're not cheap, but they're worth it.
To piggyback, I watched their site for almost a year before buying my 590 in October. I've never seen a sale over 10% on the grills themselves, so this is a pretty decent deal.
Pics or it didn't happen. I don't make the rules.
I've had a Weber gasser for a decade and it's rock solid. I'd take a serious look at those if I were you.
Yeah, Webers are generally good for 8-10 years (assuming you take care of them properly) before you'll have to start replacing some parts once in awhile. But that's usually pretty easy to handle and not terribly expensive, especially considering how long you'll go before needing to replace the part again.
