GPSrChive Discussion Forum

After another 13 km trail run on exactly the same route (this time with the GPSMAP 65s, which arrived three days ago) and some more in-depth play* with both the 66sr and the 65s, here my updated first impressions of the 66sr in direct comparison to the 65s (addendum to viewtopic.php?p=8351#p8351):

Pros:

• It seems to be slightly more accurate
• It takes less time to get an initial GPS fix
• The reported GPS elevation is more accurate

Cons:

• The barometer response time is much slower
• Screen readability without backlighting is significantly worse
• It can happen that button presses do not register despite tactile feedback

Things I personally don't really care about but still surprised me:

• There is significantly less free space on the internal memory

Even now that I own both devices, I still don't know which one to choose. I'll probably keep both for now and eventually sell the 66sr when I'm done with it, unless the difference in GPS performance is greater than it seems at first glance.

*) I almost had an orgasm when I plugged the Mini-USB connector into the 65s for the first time.

Let us know when you want to sell the 66sr, we need one more!

I did a short hike with both devices through at least partly quite demanding terrain:

I superimposed the 65s and 66sr Elevation plots you provided to have a closer look, and they appear quite similar!

Certainly good enough for hiking purposes, but the 66sr seems to drift (it was a round trip), and I had to manually offset the 66sr by 10 m to match it with the 65s, even though I had calibrated both at the same elevation a few minutes earlier. The actual elevation difference between the two looked like this:

It is decided. The 65s will replace my 64s and will be a decent upgrade overall, although like the 66sr it sometimes has trouble finding Galileo satellites, and its altimeter also seems to be subject to more drift than the 64s's:

I have taken both the GPSMAP 65s and the GPSMAP 66sr on a real hike, and I have to say that both are fantastic, and that - despite the fact that they both fail horribly at times - it is hard to tell the difference between the two devices by mere visual inspection of the recorded tracks. Still, I have to admit that the 66sr slightly outperforms the 65s.

Here is an updated list of observations:

• The calculated total ascent differs significantly even at normal hiking speed
• Route calculation on the 66sr is slower but the result is better (with TOPO Germany PRO)
• The 66sr's display is definitely better than I had originally expected (especially when it comes to color rendering)
• The 66sr applies twice as much smoothing as the 65s when calculating the speed of movement - which I actually like

Track analysis:

• track_analysis_65s.png
  track_analysis_66sr.png
• horizontal_offset.png
• elevation_difference.png

Screenshots:

• 65s-hike.png
• 66sr-hike.png

According to komoot, the total ascent at the point on the route where the screenshots were taken is about 380m (which seems plausible).

So... Are you still sticking with the GPSMAP 65 as your replacement, or the 66sr?

Yes, and even if the 66sr had neither altimeter nor routing issues, I would still prefer the 65s, but that is ultimately a personal choice, and I completely understand if someone with different needs comes to a different conclusion.

I had a 65s but I sold it then I bought a 66sr, in fact I may be the opposite of other users, which I don't like on the 65s the screen is the same as the 64s, and I don't like NiMh batteries (I've only had Garmins with two NiMh batteries) which, after having tried several brands including Eneloop, don't last long so you always have to have a spare set on you.
Unlike the 66sr which has a good battery that lasts about 30 hours, and I like these batteries, I don't do long hikes over several days I have passed the age, so 30 hours is enough for me and you can always bring a power bank.
And then its excellent screen which is precise, very fine and easily readable.