I came across a 220 V plug in a box of electrical parts while looking for something else.
!
Grabbed an old computer cord and changed the plug. Ran a couple quick comparisons.
Our “110” outlets are actually 122VAC, so the “220” is 244 VAC.
Started both tests with bed and chamber at 28 °C, set bed to 90 °C, measured time to temp with a stopwatch.
“110” took 6 minutes and 6 seconds.
“220” took about 53 seconds, maybe a second or two less because I looked away and stopped the timer a tad late. The numbers were changing quickly.
I think I’ll stay on 220. 
110 promises a slightly higher max bed temperature, but I’ve not needed that yet and it’s easy enough to change cords if I do.