Anything that isn't directly addressed to someone in a thread usually is pointed towards the OP.

(was not towards you)
You can see both sides, and you can have success both ways. I just know with my tap water, and my algae scrubber I don't have to do water changes for months on end. All trace elements stay up until the 3 month period. If my tap water wasn't gold coming from the sink I would probably own an ro/di unit as well. My tap water has high phosphates but I have ways of fixing that, the benefits far out weigh the issues.
Also I do advise using a calcium block and other means of mineral adder to your RO unit. It's healthier to drink tap water for a reason!