I've significant time with both, including one type, and one research sim that were fitted with both.
In my opinion, IF the FCMC and stick force gradients are similar, and any sidestick arrangement provides an adequate armrest arrangement behind it, workloads are similar for similar tasks.
However, those things aren't always the same - sticks tend to usually have smaller deadbands, be mechanised with lower stick force gradients and tend to have different geometries. So, it's very hard to compare apples-with-apples when comparing sticks with yokes.
But to say that a stick creates greater workload for similar tasks than a yoke, in my opinion, overly simplifies things. In an airliner, for typical airliner manoeuvring tasks, comparing a typical airline yoke to a short low-force sidestick, quite possibly - but that's comparing apples with oranges.
G