New cfs_pre_render_fields function

I love the idea behind your cfs_pre_render_fields function in 1.8.8.
However, it fell a little short of how far I was hoping it would allow me to extend CFS. I was hoping to use it so that I could run through the actual items of each field for each post, and filter those. For example, I have a site where posts have a user field. I want to restrict which users appear in that field by which user role the logged in user is. I.e. admins can access all users in that list, contributors can only access certain users. I am currently doing this through jquery, but I would LOVE the ability to do this by using a filter. Any pointers, or would you consider extending CFS to allow for this?

https://www.ads-software.com/extend/plugins/custom-field-suite/