You are correct, there are no issues with 10AWG while running multiple panels in series using a MPPT controller.
With a Renogy 400watt kit with Rover MPPT, I was seeing 72v and less then 6 amps to the controller.
Using an estimated 25' run, we were looking at .4% drop, which basically negligible.
Right now I'm to 600 watts - 2 parallel 300 watt strings - and I'm seeing more like 8-9amps at 56v...voltage drop again is way below 2%, though higher, at .9%.
Here is the site I use to make those calculations:
http://www.rapidtables.com/calc/wire...calculator.htm
There is a group out there that prefers running all panels in parallel @12V (really 18v) and running a PWM controller. As you can imagine with the low voltage, and potentially high amperages, wire size becomes much more important.