1/8 buggy tires are lighter than most typical 1/10 treads. Yes there is more leverage on the hub but the tires/wheels are lighter which will help.
I have been running masher 2k's on my .5 for awhile and the bearings have not gotten sloppy yet. I would be willing to change out the bearings or possibly replace a hub once a year to have the benefit of running 1/8 buggy tires.