Are superzooms superior to cheaper DSLR tele glass?

There's more to it than the glass. Superzooms today do have good glass and can take great clear crisp shots in good light, but the advantage of the DSLRs becomes apparent in low light / high iso situations, even with lower-priced third party glass. So it depends on what you are shooting and in what conditions. If the situation and lens demands more than iso 400 or so, the superzoom images begin to degrade quickly as the iso increases. DSLRs produce acceptable results at much higher isos.