I do own a USP Compact .45 which I absolutely adore. I carry cocked and locked and the USPC is a workhorse. I still plan to get a fullsize USP in the future.
But why settle for one or the other when you can have both?
What I always liked about the 1911 was its slimness of the gun as well as the single stack magazines. Most of all a well-built 1911 can have the sweetest trigger you're ever going to find. In terms of combat practicality I can still shoot the lights out with my Glock's trigger though.
All in all, this wasn't a logical decision ... it was more an emotional reflex.
Any advice on full sized USPs? I generally don't like guns that are bigger than they need to be - but the USP .45 has a 12 rd capacity and I understand it shoots quite nicely. (And I'd rather have a USP than a ParaOrd or double-stack 1911) My USPC is not as big as I thougt it'd be - probably the oversized trigger guard gives it an illusion of bulk.
IMO - the USP is supposed to be a .45 ... why anyone would shoot 9 or 40 in one is beyond me - IMO it's like getting a S&W N-frame .32 (no such thing) - it just don't compute.