I've grown in soil/hydro and did the flush and no flush on plenty of crops. What i've noticed is if you grow it the right way there are only subtle differences. To the people who say there is a chemy taste or smell when you don't flush, the reason is because you didn't cure it properly. Even the differences between a hydro or soil grown product is subtle. The only difference i noticed in a hydro grown product instead of soil is the finish time and how faster they grow. The final product still taste the same and be just as potent. The key is the way you cure the final product, this is what makes the bud taste and burn properly.
After growing for a while and giving different products to my patients i've come to the conclusion that flushing doesn't really make a big difference. If you have a good strain that is grown properly, the key to getting a good final product is the cure. I do mine in mason jars for at least a month and when it is ready for consumption it taste awesome.
I'm not saying what is right or wrong if you flush or not, what i am saying is that you will not be able to tell the difference between a flushed product and non-flushed product if it is cured correctly. I've tried this with my patients and none of them could tell the difference sometimes they were even wrong. My suggestion to everyone is do what you feel is right for your grow, but don't take everyones word as science. People in this hobby think that there is only one right way of doing things and after growing for over 10 years i've realized that what works for you might not work for someone else. Just my 2 cents, Happy Growing Everyone!!!