as far as one's concerned

I would say, "yes," but you might be giving up a certain "dismissive" quality.  In that regard it's like, "For all I know," which may be used to introduce a sarcasm, or a perfectly serious and innocent speculation.  Of course, "in my opinion" is sometimes used that way too.

They want to tear up the old golf course and put in a housing development.  In my opinion, that would be a real shame.  For all I know, they're just a bunch of crooks, trying to rip us off.   As far as I''m  concerned, they can all go pound sand.

Hi Anon,

I'd say all three of the "introductory expressions" may be used to precede the expression of positive, sincere, or serious opinions.  "As far as I'm concerned" means what it says  -   to the extent that I'm involved, or should be entitled to comment on it.   "For all I know" means I have limited knowledge of it, but this is what I believe may be the case.

And yes, all three may be used to introduce negative, derrogatory, and sarcastic remarks; in my opinion being the least given of the three to this sort of usage  -  as I tried to show in my first post.

Re go pound sand, I'm afraid The Urban Dictionary lists some frightening uses beyond the one I had in mind, which is similar to the use of "go to hell."

Best wishes, - A

Anonymous

Do you mean 'for all I know' means 'as far as I know'?   I didn't say that, but I'd definitely agree to it, with the caveat that "for all I know" would be the preferred choice in sarcastic usage.

How about other similar expressions, such as 'in my view', 'to my mind', etc.? Is their usage more like 'in my opinion'?  I'd say, "yes"   -    for serious-minded people.

I meant "limited knowledge" in the sense of VERY limited knowledge.  (Or as your dictionary says, I don't know something.)  Your dictionary's expression "that it's not important to you" is what I meant by "dismissive" in an earlier post.  "I think it might be that" carries the first aspect (don't know) but it doesn't carry the second one (don't care.)  Therefore it would not be able to carry the sarcastic tone which may be associated with "for all I know."

Remember, all or these expressions may be used in a perfectly civil way.  But "for all I know" and "as far as I'm concerned" are often used to introduce derogatory or grossly insulting remarks.

I hasten to note that this thread took a turn I didn't anticipate   -   which of course is a great feature of this sort of discussion.  You never know where a thread may lead.  I don't want to leave you with the impression I'm opposed in any way to strong disagreement.  My original point was that by replacing "as far as I'm concerned" with "in my opinion" you stood to lose a bit of the potentially sarcastic flavor.  I didn't mean to open up a can of worms.  It takes a long time to learn the difference in a language between strong disagreement and libel, but it's important work.

  - A.