I'll throw my experiences / opinion down on this.
I've been growing for two years. I started out flushing with completely clean water when my feeding schedule is complete (65 Days total). I experienced absolutely no negatives from this...buds come out tasting good and not harsh at all as long as I flushed for at least 12 days. Growth seemed to slow a bit but not significantly.
Then, I started reading everything that I'm sure you've come across about flushing being bad for the plant, etc. So I started doing research. As usual, with cannabis finding anything consistent or proven is about impossible. So, I decided to kinda ride down the middle of everything I read. Instead of flushing with clean water, I "flush" with Earth Juice Sugar Peak Grand Finale which is basically Molasses on steroids (0-6-4) and Bloom Final (the ratio is less than 1-1-1). Both nutrients are designed to be used during the "flushing" period of your grows. As long as I use just these two for at least two weeks, I have noticed NO difference in smoothness or taste. I have also noticed definitive increases in bud growth throughout this period while using these two nutes. I will never go back to flushing with straight water. At the very least, if you are going to still use full nutrients avoid anything with high levels of nitrogen. Regardless, I would highly recommend at least giving the Grand Finale a shot because I absolutely love it.