HTC Desire S - state of charge 74% - iSmart Port - 5.04V / 0.86A
HTC Desire S - state of charge 74% - Standard Port - 5.07V / 0.48a
Amazon Fire HDX - charge level 75% - iSmart Port - 4.99V / 1.44A
Amazon Fire HDX - charge level 75% - Standard Port - 4.99V / 1.44A
(That's amazing, the default port is indicated only with 1.2A and loads on both ports (at least with this state of charge) at the same speed.)
iPad 3 - state of charge 2% - iSmart Port - 5.00V / 1.33A
iPad 3 - state of charge 2% - default port - 5.00V / 0.93a
iPhone 5S - charge level 55% - iSmart Port - 5.03V / 0.98a
iPhone 5S - charge level 55% - Standard Port - 5.03V / 0.98a
The two Apple devices I find surprising - the normal default port is thus suitable to invite you iPhone quickly. I would have expected that there flow only the usual 0.5A and invites the iPhone forever.
I repeated the test with four connected devices, the voltage / current differences are negligible.
Conclusion: All (my) devices load perfectly, even the two standard ports are very useful (small exception is the HTC).