6.5SLR is better - just a minor modification that give major improvement: better brass life, better barrel life and less bolt thrust.
The reamer drawing I saw for the SLR had a long throat that may not be optimum for shooting out of a short action magazine. I remember seeing a different drawing for an "SLRS" or something along those lines that was better suited for magazine fed rifles. I can't remember where I found that print though. Thoughts?