I like Nakiri's for smaller veg prep stuff like Desol; I am rarely doing any tip work where I need a fine pointy tip, usually just julienne or dicing. Using the nakiri for these tasks also saves the edges on my gyuto's. I do a much higher polish on my Nakiri edges than I do on the Gyuto since I want more tooth for slicing and trimming proteins on the gyuto. A Kohetsu 210mm is a laser class knife and is still decently tall at the heel to have good knuckle clearance. The Kohetsu 240mm is a bit beefier overall and in the grind as well compared to the 210mm, so it's a lightweight gyuto that can work as an all arounder/midweight.
The 240mm usually will have more of a flat spot than a 210mm, which makes veggie work a bit easier (less accordianing in a push cut). By the time I pinch grip the 210mm, a good bit of the flat spot is now taken up by my fingers over the spine, so it feels even shorter. If I need a pointy tip, well, that's when the 150mm petty comes out, which is rare. I find myself using a double bevel Funayuki more often that I do a petty; pointy tip if I need it, but also some height and flat spot for veggies, little curve for trimming proteins.
What I have found on Sweet Potatoes is that I prefer a 240mm midweight with a full convexing (tanaka sekiso) compared to a Workhorse, which generally has a lower grind height (anryu and goko). Even my Laser (Kono HD Ultimatum 270, reground Addict 2 in 52100) gets beat out in sweet potatoes by my midweights. But both the Tanaka Sekiso and Richmond Laser AS gyuto's get beat out by their respective Nakiri's in sweet potatoes.
So I would look for a 240mm midweight
Kohetsu 210mm is a great AS core/SS clad Laser.