I'm 6'2" and though I pulled 505 for 2 and 520 from the floor some months ago, a couple set backs- tweaked lower back, illness, moving, etc. kept me from approaching again. I finally was able to pull 500 for 3 from lower shin level Sat. Im not sure how that stacks up with the previous lifts from flat on the floor. ( I did some ridicuous weights from the knees, the past year, but that's kinda off the focus of where Im directing this Im a fan of the lift, so any deadlifters please chime in.
Rack / partial deadlifts carry many of the same benefits as a traditional DL, but have a few advantages as well.
For starters, when pulling from the floor, the first 1/3 of the movement puts a lot of stress on the low back / lumbar region.
If you’ve got problems down there (it sounds like you do) eliminating the bottom most portion of the ROM reduces most of that stress.
Also, if you’re training for physique, pulling from the ground tends to thicken the waist on many trainers over time.
That, in itself, isn’t a bad thing, but if you’re going for any kind of V-taper, you probably want to try to keep that area on the slimmer side.
Opinions:
It really depends on who you ask.
Some folks claim rack deads are easier because you shorten the stroke. Others say they’re harder because you take the legs out of the equation.
Both statements can be true depending on where you position the bar as your starting point.
I like to set the bar right at the point where I feel that my back takes over the workload from my legs, which for my body frame, is just below the kneecap.
If I start any lower, I feel like my legs are doing too much work, and the bar has gained momentum by the time it gets to where my back takes over.
Starting higher, I feel like I’m robbing my back of its full ROM.
IMO you're on the right track, and I would keep doing what you're doing.