I've got a full size H&K .40 S&W
I don't think it's any different in size from the H&K .45. It's the most accurate (to me) pistol I've shot so far. The 1911 is a classic, fits most hands like no other, and if one spends a little extra, its accuracy is unparalleled.
But, if you want those things, along with complete RELIABILITY out of the box, an H&K USP .45 might be the answer.
And by the way, I own two Kimber 1911's which are NOW completely reliable. One right out of the box, and the other AFTER two trips to the factory. I also owned a Rock Island Armory 1911 which was totally unreliable (I know, I know, SOME of then are good weapons, I got a lemon) from the start. I sold it (with full disclosure) for a loss.
My H&K has NEVER failed. EVER. About 5000 rds and going strong.