I don't use three blade heads, I have some , sharpened them but never used them. And, No, I don't cary the slab with me,(my pack is heavy enough), it lives on my bench. I only used it to get the initial edge, after that it is just a matter of touching them up from time to time. I am using Zwickey deltas single bevel ground this year. I keep them sharp with an angled diamond setup, works great!! As far as knives go I have been sharpening them for years, I have a routine that works for me. I would have to show you in person.
Good Luck
Mike