The main problem I see is that there will be a fairly large pH spike between water parameters. Check the ph of your tap water and then compare that to your tank water. 9 times out of 10 it's more than fish should be subjected to.
That's why 50% is about the most water that is recommended to change out at once.
"The simplest explanation for some phenomenon is more likely to be accurate than more complicated explanations." -Occam's razor