I came to the Garmin world having used the Sigma ROX platform for 4 years. The Rox 9 was overall a great computer that served me well. My Garmin 510 is a radical improvement.
Still there are a few things that the ROX platform did better.
First, the Training center software provided a multitide of graphs that are not available on Garmin Connect.
1) A multi line graph where various data elements are plotted on the same time axis.
2) Bar graphs over weeks and months allowing easy visuals of your mileage.
I dont think Ill be going to the new Rox 10 anytime soon. But I do miss some visuals that Garmin Connect could provide but does not.
Last word... one of the hardware features I miss from the Rox is average speed to the hundredths. It would be great to see this in future firmware versions.