Only thing that worried me was a lot of posts I have read said the 2" drop spindles were only getting people 1"-1 1/2" drop and not the full 2". With my luck I'd be one of the guys to only see 1".
To be clear, I'm looking at doing the drop spindles plus the struts to make sure I'm able to get the full 2" drop.
You also have to consider the fact that the majority of those dropping don't bother to measure, or measure half-assed before they install the drop parts. Also, with the suspension taken apart for the duration of their work, it expands and some of them post before allowing it to settle. Or, they do other work such as replacing control arms and tighten the bolts with the weight off the suspension. Maybe they measure at a different point or with the car on a different, possibly slightly sloped surface. Or they change wheels during the drop. Or they have an empty tank of fuel when they measure the "after" height when it was full for the "before" measurement. Or, just like these things do, the suspension rests at random heights after every drive. I park in the same spot on my driveway and sometimes it'll be about 1/4" higher. But it'll be "right" after a day or so of sitting.
I try to be very precise to minimize variables when documenting for comparison. With suspension mods, I measure to the 1/8th and sometimes to the 1/16th, being careful to measure the same points with the same tape measure.
There are just too many factors when comparing to others' posts. The fact is that spindles are "hard" parts. I've measured my McG spindles and compared to the BT spindles on my neighbor's Tahoe. His is dropped the same as mine with spindles and struts. Mine definitely, and precisely, had the spindle 1.75" higher than stock whereas his BT spindles had it 2" higher. His Tahoe also varies ~1/4" after drives.
Those reporting 1"-1.5" of drop from spindles messed up somewhere, either in their labor or measuring.
If it were me, I'd get the spindles first then the struts later. You might decide you're fine with whatever you end up with and don't wanna alter the ride any. You don't need to uninstall the spindles or anything like that to replace the struts, so there's no double-working.
If you get the BT spindles, there's no reason why you shouldn't get the full 2" drop. If you want the McG spindles for their (possibly negligible?) attributes, you should expect 1.75" and will require further measures if you want a full 2" drop or more. Just know that, unless you have a base (LS) or maybe even an LT, or any non-active suspension model, you might get a firmer ride with the BT struts. Or, it'll ride "fine", but you'll feel more of the shocks transmitted from hitting cracks, blow-ups and other irregularities in the road.