They ARE the same case size. Because of which I went with 8.0 HO instead of the 6.0 HO. But according to tests on the interwebs & YT, the 6.0 HO actually can provide more power for those tools that need them due to the higher rated current drain but less capacity cells found in the 6.0 HO.
I don't really care much about that for the tools I have. For a battery pack so big & heavy I'd rather have the increased runtime. With that said I currently only own one 8.0 HO pack. I only got it cause I got a good deal on it & to have in case my 9.0 ever dies. Lucky for me my 9.0 doesn't seem to be one of the problem ones. Ironically my 8.0 died & I had to send it in for warranty which MW replaced. Then my buddy's 8.0 died a month later, also replaced by MW.
Speaking of the 9.0, what I found interesting is that my 9.0 weighs exactly the same as the 8.0.
