Phoney said..
Does anyone here use the same steamer for spearfishing as kiting?
As far as I can tell it's only the cammo that sets the spearing ones apart and I'd rather only buy one than two.
You're correct, the lower end spearing suits (<$200 or so) are essentially the same as a lower end surf suit (with the addition of a loading pad on the chest). These will be fine for kiting.
Higher end spearing suits (which are almost always 2 piece - pants and jacket) are a fair bit different though. They are generally made out of open cell neoprene which is very sticky when dry and almost impossible to get into without wetting the suit or using lubricant (e.g. shampoo, sex lube). These suits are really warm and comfy once on, but would be a pain for kiting.