M.M.
S.,
I don't think there is a right or wrong about crib vs. toddler bed. My son was a head bumper too and always slept pressed up against the bars in one corner of his crib, but I guess he was comfy because he slept great like that.
When we did transition him at around age 2 1/2, he fell out quite a bit and would wake up crying. We did put pillows on the floor at times but the best thing we did was use one of those foam noodles for swimming and put it on the exposed side of his bed (under the sheet, on the edge). That was enough of an edge to stop him from rolling out and now he sleeps fine without it and doesn't fall out.
Lastly, if you do keep him in the crib, I wouldn't use bumpers as they are supposed to be more harmful than good at his age becuz he is at that climbing age and could use them for that.