80mbps is not adequate for actual 4k. Only for heavily compressed 4k that is essentially full HD due to the compression artifacts. This would be pretty good for a DSLR if you are just spraying and praying.
Might pick up a couple for that use.
But for 4k, don't screw around. You are going to have to get UHS-II and spend close to $100 per. The Sony G series have been solid for me.