Anyone have experience with digital radon detectors?

I just found out that some homes in my area have very high radon levels. My first reaction was to get one of those canisters they sell at hardware stores to have our home tested. After a little research I found that there are digital radon detector products that monitors radon level continuously.
Does anyone know if they are useful/accurate or if they have serious limitations?
What's your experience with these products? Do you know of make/models that you'd recommend? If so, where did you get your detector from and how much did you pay for it?
Many thanks.
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