I would measure ~1.5a out of retractable cables on my Galaxy S4 with OEM charger (a 2A capable charger) compared to the full ~2A with the OEM cable. I now ger about the same on my Moto X 2014 with the retractable cable and Samsung charger (the charger included with the Moto X 2014 is only 1A, even though it's dual-USB). I can live with ~1.5a when traveling, and use a 1.5a Samsung charger (that came with an old Samsung Rugby Pro) when traveling anyway.

I'm about to switch back to a Asus T100TAM from the Surface Pro, and the Asus charges from USB... back when I had the original T100TA, both it and my S4 would charge just fine off of retractable cables and this 17w/3.4A dual-USB charger. I'll probably dig it back out, or maybe get one of these 20w Anker chargers with PowerIQ ports.