[eJM]

That's not the same. If you have to devise special code, whether that be template edits or a plug-in, you are giving the spiders an advantage website visitors do not have. If the content is blocked from view until a user meets certain requirements, like registering, agreeing to terms and being added to a special usergroup, then you are causing the spiders to circumvent these requirements, which the normal user cannot do.

If the possibility exists for a user of this modification to be banned or penalized by Google or another popular search engine, you should state it in the modification description. If you have proof that search engines will not punish users of this mod, then there isn't a problem. It's my opinion that you have an ethical responsibility to your customers (a customer isn't always someone who pays a fee) to keep them informed of any possible consequences from using this software.

Jim