Maybe I'm terrible at following tutorials, but I've used REW and a MiniDSP with several speakers and subwoofer sytems... I've never gotten close to GLM results with subwoofer integration or bass correction.
There's a large value for me in GLM taking 15 minutes to play with and even EQ to taste, vs spending ~10 hours over a week on a system following tutorials, reading, calibrating, measuring, and repeating.
If anyone has used Dirac and GLM and prefers Dirac, then long term that will save money because of the expense of Genelec SAM speakers and subs... Even used, a dual 12" Genelec 7271 is $2500, and for that you could get a dual 15" Rythmik G25HP.