This is actually exactly what I've been doing...not really happy with my results (there could be many reasons). I am going to switch to Will's method until I hear or read something credible disproving LCR...I've been reading a lot of articles/blogs last few days and I am so far convinced. But I'm a noob and don't really know much.
Not trying to bash your approach at all, I just thought it was cool that it was the same thing I came up with. When you say "t takes some effort to get the stereo balance correct though.", what seems to affect that? Does it change from amp to amp for you, or from song/song type? I always never had any indication that I was getting it "right", just seemed like I was fumbling in the dark when panning. I did use the 75-90 range though.
I've been experimenting of late and seems like panning in different ways helps on different tracks. I'd be wary of any hard and fast rule or formula. The LCR rule is a good approach, but I've also seen metal guys often pan away from the extremes with good results, so it's by no means gospel.