Wanted to chime in here because I'm interested in doing similar in my 2009 XL SLT, and had a bad experience with this in the past with my old 2009 Sierra SLT.
I installed 4600s in the rear of my sierra myself, and bought the 4600s for the front and asked my local shop to disassemble and re-build the struts for me with the bilsteins in them so I could swap them in easily without risking life and limb with a spring compressor. Long story short, they could not get my factory struts apart, and neither could I even with a LARGE hydraulic press. I ended up giving up and returning the bilstein shocks for the front and buying Monroe loaded struts to get my truck back on the road.
I am eventually going to have to freshen up the suspension on my Yukon XL so I am trying to take notes on what options there are for loaded strut assemblies to avoid losing my mind again on disassembling my factory struts. However, if this is an isolated incident and most folks don't have any issues disassembling the factory struts then maybe I'll give it another go.
