So far the Garmin has been pretty good. Only trouble and is actually user error has been forgetting to hit the play button once under way. I have the mileage in the lower right hand corner and forget about it. So I haven't actually recorded all of my rides.
As far as interface I really like how you can set it up however you want. I put speed on top cadence in the middle and heart rate on the bottom. The two little squares on the very bottom have time and distance.
The 510 aquires satellite pretty quick maybe 30 seconds to one minute and it aquires the heart rate monitor, speed/cadence sensor and my phone. Perfect amount of time to walk to close the garage. I then ride to the end of the block and its ready to go. Same time as I start Strava on my phone.
Havent really lost satellite but have lost the speed/cadence sensor on one ride.
Like you I use my iPhone, ipad and Macbook for all of my items. Happy that I know longer have to wear the watch for HRM.
Comparing the Garmin and Strava(iPhone) on my last ride:
Distance the same by .1 miles
Avg speed Garmin 18.93 Strava 19.2
Max speed Garmin 40.59 Strava 39.8
Ascent Garmin 1437' Strava 875' BIG difference here! However Garmin is ascent and Strava is Elevation Gain.....
I would be really frustrated if I was on my 3rd device!
I hope you get it sorted. I really wanted the Cateye as my double wireless Cateye is awesome on my winter ride and on the trainer.