After two weeks of side-by-side usage, I've concluded that these watches are targeted at very different markets. Furthermore, in many respects, it seems like neither watch is totally ready for prime-time. Both have nice feature sets, but they each seem to be lacking some very important features to make them truly useful across several sports. The Suunto X9i seems to be targeted and more useful to the climbing crowd, whereas the Garmin Forerunner 405 seems targeted at the fitness/jogging crowd. Neither has the complete feature set that the above-average hiker/trail runner/mountain biker needs. Thus, if you purchase either, you have to accept the compromises inherit in one or the other.
If I was pressed to recommend one over the other, I very hesitantly lean towards the Garmin Forerunner 405 due to smaller size, better battery life, faster GPS synch, slightly better navigation screen and of course, lower price. I'm hesitant because of several important cons which I elaborate on below.
Battery Life (w/ GPS): 4.5hr (X9i) vs. 8hr (405)
Battery Life (w/o GPS): 16d. (X9i) vs. 12d. (405)
Size: X9i is larger in every dimension than 405
Weight: 74g (X9i) vs. 60g (405)
Water Resistence: 100m (X9i) vs. 3m (405)
Heart Rate Monitor: No (X9i) vs. Yes (405)
Outside Temperature: Yes(X9i) vs. No (405)
CONS: Garmin Forerunner 405
1) Does not display raw latitude/longitude position on standard screen. You can save a waypoint, which they call 'location', and then edit that point to see the latitude/longitude (displayed in non-decimal format).
2) Does not have On/Off button to save battery-life.
3) Comes with very basic software with limited maps. Cannot export tracks into GPX format.
4) Difficult to upload waypoints for future route.
5) Limited to WGS84 map datum (limits international usage of tracks)
PROS: Garmin Forerunner 405
1) Easy to use menu system.
2) Fast GPS satellite synching.
3) Can connect to heart rate monitor.
4) If you can get waypoints loaded, there is a nice screen that shows the direction/distance to the selected waypoint.
5) Great fitness monitoring screens and many are customizable.
CONS: Sunnto X9i
1) Large physical size.
2) Poor battery life with GPS on.
3) Slow GPS satellite synching.
4) Difficult to use and complex menu system with 5 buttons.
5) Does not have On/Off button to save battery-life.
6) GPS tracks, which they call 'logs', tend to have jumps/errors when GPS drops out, which is often.
7) Comes with very basic software with no maps.
8) No screen to show direction to a selected waypoint.
9) Limited to WGS84 map datum (limits international usage of tracks)
10) Suggested Retail Price is 25% more than the Garmin 405.
PROS: Suunto X9i
1) Does display raw latitude/longitude position on Position screen, but in non-decimal format.
2) Does have temperature feature.