Ok here are my thoughts on the matter: I think staying at a lower town hall just to grind out heroes doesn't make any sense. When you upgrade to a higher townhall, you have more defenses to guard your DE and protect your base. You also get stronger troops and more spells which can help you get to that DE collector in the core of most bases. The main reason not to go to a higher townhall is the loot penalty. With that in mind, the loot penalty only applies to town halls which are 2 levels under you. Since it's very unlikely that you will be stealing DE from TH7s or TH8s, the loot penalty wont effect you. That's my reasoning for upgrading rather than grinding out heroes at TH9.
However, the loot penalty will apply to walls, so I wouldn't tell you to rush to TH10. My opinion on the matter, which I give to most people, is that if you're bored, go up. If you don't mind grinding them out, then stay down there. Either way, you should be fine to go to TH10 now, and like I said above, I definitely wouldn't stay down there for the heroes.





