How are companies handling W4 form?

Summary

Curious as to what most companies are doing for W4

Content

We are mid-implementation and need to make a decision regarding W4 and using a passport service or creating the user-defined form ourselves. I know from past experiences maintaining the UDF can be a challenge. 

What are you doing for W4? Are there any other options that meet compliance standards for the W4 form besides passport service and building the entire form out as a user-defined form. We also need to send a number of the fields to core and payroll so we have to be able to extract them via interface.