When I comment on blogs I try to contribute to the conversation and look at it as an opportunity to make contact with potential customers as well as expanding our link profile. I would feel really uncomfortable entering anything other than a name - depending on circumstances either the brand name or a personal id - in the name field as I think this would be repellent to the people I want to connect with.
In terms of link acquisition, blog comments are a low effort, low value option. I don't see why people would expect using exact match anchor text to give a huge boost to the value of the link - of course the search engines are aware that user generated content is a magnet for spammers and I'm sure they have ways of discounting those links.
I think the best approach to blog commenting is contribute to a community and form real relationships. That way you have the immediate benefits of engaging with your market, with the added bonus that people who trust you and value your contribution are more likely to link to you. I've spent too much time deleting comment spam on our blogs to think much of anyone using that tactic - it's a good way to guarantee I won't check your site out!