I have a N3DS. As for when I last tried, would have been 8 to 12 months ago max.

And the Vita doesn’t has multiple days of all day gaming, it has about the same amount of play time as the 3DS, but it can be left in sleep mode for much longer. After 2-3 days of being in sleep mode (normal, not an emulator), the 3DS battery is drained and i need to recharge it. The Vita can sit for a week or 2 and barely have lost any power.