The 551 and 556 are nice, but the full built models like the 525 and 943 are another class. There's nothing wrong with the Grips, but I'd skip them and go straight to the real thing.
The 940 series is a true classic, I think - the ergos are close to great and the knives pack an enormous amount of edge into the handle size. The 525 arguably is even better in the hand, but does have a shorter blade and a handle that is neither so smooth nor so slim in the pocket. If at all possible you should try to handle both and see which one your hand falls in love with.