I have only done a few dozen bamboo shafts, and used mostly the "Martha Stewart" tomato stakes, but I was under the impresssion that carmelizing was mandatory, and have always done it that way.
I got this idea from a YouTube vid where an old Korean gentleman was making Korean-style arrows from Japanese/Korean arrow bamboo. He had them over a charcoal fire and the narrator mentioned that the shaft must be "cooked" evenly or it would go crooked later. So, I always cooked them evenly after straightening.
Pretty jealous of you guys who can go cut cane. Doesn't grow anywhere I know of out here in the West, and I have about given up on tomato stake. I have turned out some fine arrows, but the quality seems to have dropped a lot and I get about 2 usable shafts from a pack of 10, and they aren't anywhere close in spine.