There are alot of guys in k1 with this background. one of my favorites is yuya yamamoto. his fights are awesome. the guy has some seriously effective combos. Checkout his fight against gago drago. I think it has alot to do with fighting and training for competitions without worrying about weight classes.
Yup, the last 5 years or so, maybe even more, a lot more in K-1 are coming from shinkarate backgrounds. Over here in the USA, the few that have done shin karate come from either a karate and "Eurasian Kickboxing" background or TKD and "Eurasian kickboxing" background.
If you're not familiar with Eurasian kickboxing, look up Haru Shimanishi (cofounder of AMC and founder of HMC). Haru was the first, and one of the only ones with connections to chokushinkai and shinkarate as early as the 90s, here in the USA. Osu!