The best thing regarding k6 is that the learning curve is not steep. You can create a serious load testing solution within hours. Besides simplicity, you can generate thousands of virtual users from a single machine. k6 supports hybrid load testing out of the box. Review collected by and hosted on G2.com.

You cannot reuse your existing UI testing scripts for hybrid scenarios but create new scripts. However, the feature is still in the experimental phase, and I'm sure the support from the team will come. Review collected by and hosted on G2.com.