Very good points and a solid attitude. It's not a matter of "can't beat 'em - join 'em" rather than a good opportunity to learn what the "enemy" is up to ...
Google wouldnt ban your site if you comment spam your link on other peoples blogs. Why not? I can just as easily screw your site as I can screw mine then right? I could wipe out my competitors. This isnt how the system works.
Hey Moron, All you do is post vague bullshit telling people to PM you. Contribute to the forum or leave. Establish yourself and maybe people will consider buying whatever you are selling.
Google say they won't 'usually' penalise a site for sites linking to them, so it's not to say it won't or it hasn't happened. Either way, a poor link profile won't help and I'm sure excessive links from blog comments don't add up to a good link profile.