I've used both straight and curved and both are a pain in the back for me. I recently went to a janitorial supply house and bought a good bucket on casters with mop wringer and bought a good mop with launderable head to clean tile floors Our Scuba robot doesn't keep up satisfactorily and needs some assistance. I have no back problems swinging a heavy saturated mop as the handle is plenty long and easily reaches the floor.
I think the weed eaters are just not sized for anyone over 6" but that is just my opinion based on the ones I have used. I believe the best solution is whatever the operator is productive with that doesn't constitute a health hazard/or pain.
Pat