No, you haven't "pointed out" anything. Rather, you have expressed a contrary opinion to mine. I will leave it to others to decide for themselves which opinion has been the better argued.
I have never argued any such thing, merely that I believe NI to have at least as much strength in depth at CB as ROI.
But for the record, if you want my opinion on the relative merits of Aaron H versus those three, here it is.
Richard Dunne - Excellent CB, a cut above AH;
John O'Shea - Excellent FB, esp this season, for both club and country. However, I'm not so sure about him as a CB, especially since Ferguson has regularly preferred the much less experienced Jonny Evans to JOS whenever Vidic or Ferdinand has been injured. Also, until recently, JOS hasn't been the most popular player amongst ROI fans, whereas AH has always been a "main man" for us. And AH has been a virtual "ever present" at CB in a Fulham defence which was the fourth meanest in the EPL, and the mainstay of their finishing 7th.
Sean St. Ledger - Looks a prospect and seemed to play well in the 1st half vs Bulgaria (didn't see 2nd half). But if you are seriously saying you rate someone who has two caps, and who has never played in the top flight, over someone who has nearly 70 caps (c.50 of them as Captain), and who has played his entire club career of over 400 games for Newcastle (inc. Champions League), Aston Villa and Fulham in the EPL, then I pity you.
http://en.wikipedia.org/wiki/Aaron_Hughes
Therefore, if those 3 players were available to NI, I'd certainly have Dunne in the team at CB alongside Hughes or Evans, with O'Shea at RB, and St. Ledger nowhere.