I'm kinda a Griptilian "nut", and have both full and mini size Ritters and Regular Grips'.
It's ultimately your call if the Ritter is worth the extra, I really like them, but the 550HG Grip' is also an amazing knife for the money.
You really won't go wrong with either IMHO.
They are nice
The small one is a lil small for my hands and I do not have LARGE hands by any means. The grip is still one of my favorite, secure, easy to hold onto and use. In some circumstances a blade that flicks-open assisted would be nicer but this flicks open with a nice flick of the wrist. This will be my next purchase (The larger one as I have the small). Great KNIFE! I would buy this if I were you
(And I am a knife nut with many expensive knives)
(PIC OF SOME OF THE FAV FROM 3 YEARS AGO)
(I want to be clear in the above... my next knife is either a full size Grip. or a full sized RSK MK1 both are awesome (and VERY similar) and the RSK MK1 is only slightly more money. You can't go wrong with either.)