350 will be better if body drag is your goal. 
Check out 
http://kitesurfingschool.org/  for some tips. They have a section on body dragging. 
They key to getting upwind is to use your whole body as a rudder. The arm out and using your hand makes all the difference. Having a harness also
helps a LOT.
Odds are pretty good you won't get to upwind dragging with a small kite and no harness so just enjoy the downwind ride. DON'T go out in offshore wind.
Be SAFE ! 
 
Kites: 2.5m Profoil  , Quadrifoil XL kitesurfer, NPW 5 Danger. 
Flexifoil: 1.7m Sting, 4.9m Blade 3, 9m Blade 2.  
Flysurfer : 19m Speed 2 SA, 7m Pulse
Peter Lynn  :18m Phantom, 15m Synergy, 10m Synergy, 1200 Farc,  460 Sarc, 130 Tarc, 5m Peel, 4.2m , 6.4, 8.5 C-Quads, 3.5 LS2 single skin. 
Rides:  Flexi / P.L. Frankin'Buggy , Shaped + straight skiis, sand skis, Coyote blades. Core 95 ATB. RKB R2 ATB . 
Ken (K2)