There's tons of articles and opinions about this matter on the web. I'm sure there are the same different opinions in Seblod community.
I personally don't care about the .html suffix. Some people say its more user friendly to have URLs without it. But then, some of my clients insist on having the suffix.
I'm not too much of an SEO expert and personally think that there is a lot of fuzz about the whole subject. As long as you have interesting content on your site and not thousands of competitors, people will eventually find your site and read it.