I have the 420. It is thick but the weight is not bad at all. The handle is like holding onto a sword right up there in thickness and chunkyness with the Cold Steel Ultimate Hunter. Both offer great grip and control of the knife when you use it but they sit fat in the pocket of tighter pants like close fit jeans. If you go baggy a lot the 420 will be fine. The pocket clip it sports is one of the best factory clips I've ever used. A great low ride clip is what it is.
As a side note: Most of the appeal for me on my 420 lies in the fact that I Waved the blade so it opens as I pull the knife out of my pocket like the Emerson Waved knives do. To be perfectly honest with you I didn't like it until I did the Wave on it, and before I did the Wave I was very close to selling it. Fortunately the Wave works so great that now I carry this knife a lot.
The 'Gotham Swedge' on the blade as it is called by BM in my opinion ugly and really doesn't have any useful purpose. I did away with that when I reprofiled the blade for the Wave and in my opinion the knife looks better now than from the factory. Also, the smoothness of the axis lock makes it one of the most pocket kind Waved folders I have. I've never owned a 710 but it seems to have a lot of fans and a pretty good loyal following. I doubt you would go wrong with that one either. BM makes a great knife no matter which one you go with.
STR