Yooo well it is written in the TEK why it was proposed to used distilled one:
As it does not contain other electrolytes (but will slowly uptake CO2 forming carbonic acid and lowering its pH - dont wonder), it has more power to dissolve other things / drag them out of your bark.
+ deionized water is more likely to flow into the root bark cells and break them upon freezing. Yet I still want to check if this whole Freeze/Thaw process really makes a difference, also if deionized water does it. But as long as there is no test (which I'm aware of) doing this freeze/thaw does not take any big efforts.
If it REALLY makes a difference - I dont know. But as deionized water is pretty cheap, why not just use it?
As you already used regular water - no worries, I guess the majority of everyone uses it, but it is more that you can think that at least at this point you did not loose any efficiency upon using distilled water.
There should be a test to prove that it really improves yield, but just in theory it should do and as it is cheap you may consider it the next times if you want.