I just purchased a set of DL3 mirrors from a member here and installed them on my 2017 LT with Phil's harnesses. It took me about an hour on the driver's door since this was my first time removing the door panels and I was following his instructional video. Very easy to do. The passenger side took me 15-20 minutes because I knew exactly what I was doing by then!
The harnesses and mirrors work great! I'm just waiting on the power folding switch to arrive Wednesday so I can utilize the folding function and the install will be 100% complete. Phil is great and communicates quickly if you have questions. I highly recommend! My stock harnesses are boxed up to go back to him so he can pay it forward to someone else and I can get my $100 back!
The hardest part of the install (for me at least), was getting the five retention clips along the tops of the door panels (along the window) to release. Those things were TIGHT!!! The chrome mirror caps that came on the DL3's broke tabs (as expected), but I was able to remove my painted ones without breaking anything and transfer them over to the new mirrors. That was nerve-wracking, but I got it done.