One important note... if you upgrade RouterOS then use QuickSet, you can run into problems since the /system/default-configuration can change between version. And "new" QuickSet may not find something it expects in the config because it's expecting a default configuration from its own version, not the factory-version default configuration. This is because upgrading does not re-apply the newer default configuration, so the original defconf remains same after upgrade to newer version like 7.21rc1 – but QuickSet in 7.21rc1 may need something specific in latest defconf...
Generally, it is best to run QuickSet once from the box, then upgrade to current version. BUT if you want to run QuickSet after upgrading RouterOS from factory-version, then you can re-apply the current version defconf via /system/reset-configuration no-default=no keep-users=yes, which will get you back to something the current version's QuickSet code expects.
But...it's good @bytes filed a ticket... since MikroTik does mess things up in QuickSet more often then they should given it should be "simple" and "just work".