Nope. It's smart recording, not smart sampling; the watch still acquires a GPS location every second as with one-second recording. On older watches, smart recording saved a subset of those locations, picked by who knows what algorithm. Never seen anything from Garmin on recent watches, so we have no idea if it's the same kind of subset, or if there's a filtering process going on so that the smart GPS points are not in the same place that any of the one-second places would be. Anything calculated on the fly will be unaffected. Anything that depends on post-processing could be affected (distance calculated by third party apps from a smart recorded FIT file will be less than from a one-second file, and in either case will probably be a bit different from what the watch recorded, as there seems to be a bit of distance filtering going on). UltraTrac is another story, as the GPS is turned off a lot of the time there, which saves much more power.
As mcbadger says, Smart recording still samples every second, but writes the information to the file less frequently. For a multiday backcountry hiking trip, or an ultra where you want to keep the file size manageable, this may make sense. In most other situations, there is not much advantage to this, and you might as well stick with 1s recording.
