First, congrats! Second, I also received a SD-1 for Xmas, so I'll join in on the fun!
I have literally over a dozen dirtboxes - and I've sold/flipped others. For some reason, I never viewed the SD-1 as a must-own, must-try the way that every guitarist has tried (and often hated) the DS-1 Distortion. Part of that stems from the fact that I had an OS-2 Overdrive/Distortion, and the OD ranges on that pedal are thin and weird sounding. I probably assumed that all BOSS overdrives were like that.
All of my other "tube" overdrive pedals were of the TS-9 Tubescreamer family (TS-9 Reissue, Bad Monkey, Joyo Vintage OD, etc.). But while the similarities are obvious with the SD-1, I was surprised how transparent it is compared to my TS-9! Maybe it was just my perspective, but I felt like more of my Les Paul's inherent tone shined through with the SD-1 than a Tubescreamer. The TS-9 is great, and I'm a huge SRV fan, but when you turn on that pedal, it
becomes your sound. The mids are humped up, the highs are smoothed over, and you lose some bass.
The SD-1 has some bass loss, but less, in my opinion. Haven't tried stacking with it yet, but I can imagine how it could excel at that. Actually, it's a pretty sweet sounding classic rock OD played just by itself. Great pedal, it's an instant favorite.