2x njloco others. Although I have no experience with 3 or 2 piece longbows, my one piece is definitely a challenge and I find it is all in the bow arm. Sometimes after lots and lots of shooting I get a wiggle (collapse) in my shoulder or a muscle spasm somewhere else. but usually I find that very subtle pressure points on the grip with fingers (torque) or the heel of my hand will cause lateral deflection that I never see on my heavier TD recurve. If I keep the pressure centered on the crotch of my thumb and forefinger, I'm just fine. More weight is more stable and that's the problem with one-piece bows, but if you shoot both, you'll really see the advantage when you got to heavier one. The lighter one is more fun to shoot though.
BTW, shooting my longbow has made me much, much more accurate with my recurve.