Any of the dual frequency ADS-B Stratus receivers are much better than the Stratus 1 or 1S. Get a Stratus 2, 2S, or 3. All can accept external antennas to improve signal reception. A single frequency Stratus can't receive its own GTX330ES output which is on 1090 MHz, so can't detect ownship nor receive other ADS-B 1090ES targets without involving a ground stations to rebroadcast the signal from 1090 MHz onto 978 MHz. The reason you want to be able to receive your own ship is because then the software can read out the pressure altitude that can in turn be used to compare relative target height by comparing apples to apples, that is your pressure altitude with the target pressure altitude. Without the ability to determine your own pressure altitude, the software uses your GPS altitude verses the target's pressure altitude, which can add 500 feet or more of error. Also, believe it or not, you need to set your GTX330ES settings correctly to indicate to the ground station what type receiver you have, if any. That is the only way the ground station knows to generate the rebroadcast messages over to 978 MHz. The settings in your transponder need to match the capabilities of your receiver, so when you get a dual frequency receiver, the transponder needs to be reset. So many installeres don't know they need to match your transponder settings with your Stratus capabilities, or you just will miss a whole lot of traffic. Definitely find some sucker to buy your Stratus 1 and get your hands on one of the dual frequency units or one of the competitors and make sure your avionics shop updates the GTX330ES settings so that you broadcast to ground stations you are capable of receiving on both frequencies. The other result is that you will be able to detect ownship broadcasts and decode your ownship pressure altitude to determine an apples to apples comparison in relative altitude with a target.