I never had heard any Sheamus/HHH comparisons tbh. But now that I do think about it, they do make sense, much like ... said, he is playing that 3rd main eventer role that HHH played in '99-'01 and is arguably the top heel on RAW as well as giving many people a break between Cena's last and Orton's inevidable next WWE title run.
edit- his character reminds me more of HHH's "My time" character, when he was first tansforming into THE GAME.