I have a few friends with TDE enabled on large production databases (> 100GB) and fairly low overhead. Around 4-5% for their workload.

Overhead is workload dependent and can impact performance if the encryption load is heavy for your db or tempdb.

I give an encryption talk and in the 20 or so times I've delivered it, I have found about 20-30 people (out of the 250-300 people that have seen the talk) are using TDE. For most the overhead is low and it's a non issue. However, the majority of them have also not experienced a DR event, so they don't know about impacts for restoration under pressure and if their certificate backups are easily obtainable and good.