I posted on the other thread mate , choice would have been the thermal take - It will go fine in the define s though mate too.
The leaks were from early models, where the pipe clip joins failed , this was sorted a long time ago as far as I'm aware
Obviously electronics + water cooling there is always going to be a slight risk of failure.
I'm more inclined to air coolers myself , block of metal + fan , there's not really anything to go wrong, its a easy safe option.
The h7 is good , but if you're looking at overclocking a 6700k there is far far more headroom with the maelstrom.
At stock speeds the h7 is absolutely 100% good enough though.