Have a look at this calculator here, handy wee tool that someone much smarter than me recommends for testing confidence in system testing.

http://statpages.info/confint.html

Using the numbers from your above stats in the binomial confidence calculator, I would be reasonably confident to start to bet both of them provided you are pretty sure you are not going to affect divis.

Expected variance of SR for the systems

System 1- 72.55 - 78.01%
System 2 - 72.19 to 78.75%

Using the lowest SR there you still end with a positive ROI, 1.066% POT.