From experience I found that I loved my 50% claw better then my eth 150ed fools knockback zodumed (i know it's not something but hey, deal with what you've got). Although I used 50% cb a lot of times :\
Btw if they charge and you namelock tele and WW in their direction, will it hit them ? If yes, I still like 50% OW more...500+life is not to be messed with (with some venom with double time thing and perhaps some chaos hits) it will take only few hits to kill Hammer (having time for ow in mind

). Trick is to have 2 wofs under feet and some LS to see desynch and to mess with their heads (and to fhr tick of course). When you have those, you can move towards their side.
p.s. if they stomp you, it wont hurt that much to make 25% OW forgettable. Lets say claw has 150 more average damage. x5 for the modifier is 750 damage. Thats 125 pvp/2 = 60ish with max dr. x1.5 for deadly = 90 life per hit. And if they stomp they still have 20k deffense and 75% block. If you don't open wounds in that stomp you did nothing really.