Opencart - the right choice?

I wonder if you can help me on my decision about choosing opencart as my cms.

I need a good, reliable cms, options filter for products - THis is very important, i have seen a paid contribution which is ok,

I have seen an issue regarding duplicate content and have also seen a solution, another paid addon for $50, im not really keen on paying that when opencart itself is free?

Is it a major problem and do i really need to spend $50, is there another solution?

Hi.
1 and very important!!!
If you choose Free version of CMS for online shop: this is #1
I try all free script and nobody work like that.Plus have very module and extension that made your shop UNIQUE..
See the demo of any of our shop and think..For me this is the last and one that i use for commercial way.....Try...