This is what I posted on JBK in answer to your question. Thought I would post it again here for others to see.
It's certainly not a no no. You need to make sure the beer you serve through it is only lightly carb'd (if at all - all down to personal preference) otherwise you will get a pint of foam. I found out the hard way and I don't use sparklers on mine either.
You need a check valve inline shortly before the beer engine to stop the beer flowing back into your corny, and ideally a cask aspirator in the gas line. The aspirator just keeps a layer of co2 (aprox 1-2psi) to stop it spoiling regardless of what pressure is set on your reg. I don't have an aspirator but my check valve holds back 5psi (not tried higher) so I just give it a squirt of co2 after every few pints.