Should I start over?

I played tournement chess for years. I had some success, as a junior... And I am trying to get back into competative chess. I have only been playing unrated games on my iPhone on chess.com, but I've also been reading the forums and such...

I have noticed ALOT of strong players, recomend C/B class players avoid the kings indian, the sicilian, and the main line e4 openings in favor of more classical lines like the open game and queens gambit declined, and I assume perhaps d4 as white.

On the one hand, reflection of my knowladge shows me I have no where near mastered my current repertoire, but it's what I put all that time into years ago and the positions are farmiliar to me... Despite the rust...

The d4 would be an easy change, I played it my last year of competative chess...

But as black, is it worth "starting from scratch" to get that classical education.

Most of my study time is devoted to full games, endgames and such...

So I just wondered what those strong players who recomend a classical repertoire think in this case. Thanks

You should play what gives you pleasure and good results. And that's all.

Openings like the open Sicilian aren't the easiest. Just be aware of that. Don't let other people dictate what you should play. Club players especially play the Najdorf and the Dragon. Even the Svesnikov which is also kind of wacky. It doesn't mean they know the lines in detail.

If you want to be an all round player, (gradually) change your openings after a year or two though. You will never learn positions if you play the same thing all the time. To give you an idea: I played 3 openings with white and 3 x 2 with black over the years. I may not have been a specialist, but just playing all these positions taught me something and it kept things interesting. 

Partly, it depends on your goals.

If your goal is to improve your results in the medium-term, then studying the classical systems might be a good idea.

If your goal is to improve your understanding of the game, then playing the Sicilian and King's Indian against strong players might teach you a lot... at the cost of many lost games, of course.