First this isn't a "should I get a Droid or Eris" thread. I have a Droid and my wife has an Eris. Recently we found the CardioTrainer app and are using it to track our workouts. Today was the first day we both used our phones, and found that we got wildly different speeds and distances travelled, even though we both walked at the same pace and did the same workout. The time was the same on both phones and the map that was drawn also was the same. From what I've read it seems this would indicate a GPS signal issue. By driving the area we walked I've come to the conclusion that my phone was the more accurate of the two (actually it was very accurate). Has anyone noticed the GPS hardware in the Eris to be inferior? We have a silicone case on her phone, could this be the culprit? A few items to note: 1) My phone was in my pocket, hers was in her hand (behind moved back and forth on a much more varied arc than mine--against my leg) 2) Her phone is in a silicone case, mine is "naked" 3) Her stride is smaller than mine, but we think we may have measured them incorrectly. Another thing we thought we may try to tomorrow (along with removing the case) is to adjust the GPS filter from Good to Fair. The polling is still set to 1 second on both devices. So let me know if you've used this app and have experience with it being accurate or not.