Pretty good deal considering the 3600 is selling for between $320-340 locally depends where you are. So the gain in performance is up to 5% however likely the 3600X has the stronger IMC so for the extra $20-$30 worth it if you're after some better memory overclocks, also comes with a better CPU cooler.
The 3600X cheapest on staticice.com.au is $389 for Computer Alliance QLD but mostly $419 in NSW, VIC
3600X gives you the better cooler so there's that :)