indeed. higher concentrations and/or multiple esters are more likely to cause pain. in terms of sustanon - i also don't really love it. yet, there are many of my clients saying they feel better on sustanon than on Test E/C. As usual, that's a matter of preference. Sustanon does come with its advantages though. You can experience fast results (due to short esters), yet you're having it long lasting (due to long esters). The problem is that despite it having long esters, you still need to use it fairly often for maintaining levels in the blood stable.