IMHO it all depends on how you feel about the monthly fee for XM. If this is "in the noise", then get it. If it will bother you to pay every month, then don't get it. Truth is that both XM and ADSB radar have an unknown (to you) time delay. Neither should be used for close-in, tactical avoidance. Both are adequate for long range, strategic planning. Beyond 300 nm ADSB only shows large pixels, XM looks better. But it's just looks. Even at RV speeds that's more than an hour and a half away, and it will change before you get there.